Cloud computing means using computing resources—such as storage, applications, servers and databases—through a network instead of owning and managing everything on one local computer.
Think of it like electricity. You normally do not build a power station at home. You use electricity when needed and pay for the service. Cloud computing follows a similar idea for computing resources.
What Is Cloud Computing?
Cloud computing provides on-demand access to shared computing resources through a network, usually the internet.
These resources may include:
- Data storage
- Virtual servers
- Databases
- Applications
- Networking
- Data analytics
- Artificial intelligence tools
- Backup and recovery services
The NIST definition of cloud computing identifies five essential characteristics, three main service models and four deployment models.
How Does Cloud Computing Work?
A cloud provider operates large data centres containing:
- Physical servers
- Storage systems
- Networking equipment
- Cooling systems
- Backup power
- Security controls
Users connect to these resources through the internet or a private network.
The basic process is:
User Device → Internet → Cloud Data Centre → Application or Data
For example, when you edit a document using an online office application:
- Your browser sends a request.
- The cloud application processes it.
- Changes are stored on remote servers.
- The updated document appears on your screen.
- You may access it later from another device.
Everyday Examples of Cloud Computing
Many people use cloud computing without thinking about it.
Examples include:
- Web-based email
- Online document editing
- Cloud photo storage
- Video streaming
- Online gaming
- Website hosting
- File sharing
- Online backup
- Video meetings
- Business databases
If a service allows you to access an application or file from different devices through the internet, cloud computing may be involved.
Cloud Storage vs Cloud Computing
Cloud storage is one part of cloud computing.
Cloud Storage
Cloud storage focuses on saving and accessing files online.
Examples:
- Documents
- Photographs
- Videos
- Backups
Cloud Computing
Cloud computing can provide storage, but it can also provide:
- Processing power
- Applications
- Databases
- Networking
- Artificial intelligence
- Virtual servers
| Cloud Storage | Cloud Computing |
|---|---|
| Mainly stores files | Provides complete computing resources |
| Used for backup and sharing | Used for applications, servers and databases |
| One type of cloud service | A broader technology model |
Five Main Characteristics of Cloud Computing
NIST identifies five essential characteristics of cloud computing.
1. On-Demand Self-Service
Users can request computing resources when needed without waiting for a person at the provider to manually prepare them.
For example, a company can create a new virtual server using an online control panel.
2. Broad Network Access
Cloud services are available through a network and can be accessed using devices such as:
- Computers
- Smartphones
- Tablets
- Thin clients
Access still depends on account permissions and network availability.
3. Resource Pooling
Cloud providers share large pools of computing resources between many customers.
Customers remain logically separated even though some physical infrastructure may be shared.
4. Rapid Elasticity
Cloud resources can increase or decrease according to demand.
For example, an online shop may need extra computing power during a major sale and less power afterwards.
5. Measured Service
Cloud usage can be monitored and measured.
Customers may pay according to:
- Storage used
- Processing time
- Number of users
- Network traffic
- Requests made
This is often called a pay-as-you-go model.
Main Cloud Service Models
The three main cloud service models are:
- Infrastructure as a Service
- Platform as a Service
- Software as a Service
Infrastructure as a Service
Infrastructure as a Service, or IaaS, provides basic computing infrastructure through the cloud.
It may include:
- Virtual machines
- Storage
- Networks
- Firewalls
- Load balancers
The provider manages the physical hardware. The customer usually manages the operating system, applications and data.
Example
A company rents a virtual server to host its website instead of buying a physical server.
Platform as a Service
Platform as a Service, or PaaS, provides a managed environment for building and running applications.
It may include:
- Development tools
- Operating environment
- Database services
- Application hosting
- Testing tools
The provider manages more of the underlying infrastructure, allowing developers to focus on their application.
Example
A developer uploads website code to a cloud platform without manually configuring the complete server.
Software as a Service
Software as a Service, or SaaS, provides a complete application through a browser or mobile app.
Examples include:
- Online email
- Online office applications
- Customer-management systems
- Video-meeting platforms
- Project-management applications
The provider manages the application and infrastructure. The user normally manages their account, data and settings.
IaaS vs PaaS vs SaaS
| Service Model | Provider Gives You | You Mainly Manage |
|---|---|---|
| IaaS | Virtual infrastructure | Operating system, applications and data |
| PaaS | Development platform | Application and data |
| SaaS | Complete application | Account, settings and data |
Simple housing example
- IaaS: You rent an empty flat and arrange most things yourself.
- PaaS: You rent a furnished flat and bring your personal items.
- SaaS: You stay in a hotel where most services are already managed.
The exact responsibilities depend on the service and provider.
Cloud Deployment Models
Public Cloud
A public cloud is operated by a cloud provider and offers services to multiple customers.
Advantages:
- Easy to start
- Flexible capacity
- No need to own data-centre hardware
- Pay-as-you-go options
Challenges:
- Less physical control
- Ongoing costs
- Dependence on the provider
- Data-location and compliance questions
Private Cloud
A private cloud is used by one organisation.
It may operate:
- Inside the organisation’s own data centre
- Through a specialist provider
- Across dedicated infrastructure
Advantages:
- Greater control
- Custom security options
- Suitable for specialised requirements
Challenges:
- Higher cost
- Requires technical staff
- More maintenance responsibility
Hybrid Cloud
A hybrid cloud combines private infrastructure with public cloud services.
For example, a hospital may keep sensitive patient data in a private environment while using a public cloud for a less-sensitive public website.
Advantages:
- Flexibility
- Control of sensitive systems
- Access to public-cloud capacity
Challenges:
- More complex management
- Data integration
- Security consistency
- Network dependency
Community Cloud
A community cloud is shared by organisations with similar requirements.
Examples might include groups of:
- Government departments
- Research organisations
- Healthcare organisations
- Educational institutions
Cloud Deployment Comparison
| Public Cloud | Private Cloud | Hybrid Cloud |
|---|---|---|
| Shared provider infrastructure | Used by one organisation | Combines public and private systems |
| Easy to scale | Greater control | Flexible workload placement |
| Lower starting cost | Higher management cost | More complex to manage |
| Provider operates hardware | Organisation has more responsibility | Responsibilities are divided |
What Is Virtualisation?
Virtualisation allows one physical computer to run several virtual computers.
Each virtual machine may have its own:
- Operating system
- Applications
- Storage
- Network settings
Cloud providers use virtualisation to share physical resources efficiently while keeping customer environments logically separated.
Simple example
A powerful physical server can host:
- One virtual web server
- One virtual database server
- One virtual testing computer
They behave like separate systems even though they use the same physical hardware.
Containers
A container packages an application with the files and settings it needs to run.
Containers are generally lighter than complete virtual machines because they share parts of the host operating system.
They are useful for:
- Application development
- Testing
- Moving software between environments
- Scaling services
- Microservice architectures
Containers still require security, updates and monitoring.
What Is Serverless Computing?
Serverless computing allows developers to run code without directly managing the underlying servers.
The name can be confusing—servers still exist. The cloud provider manages them.
The developer may pay only when the code runs.
Example
A website automatically sends a welcome email whenever a new user registers. A serverless function may run only when registration occurs.
Benefits of Cloud Computing
Lower Initial Cost
Organisations may avoid purchasing expensive servers and data-centre equipment.
Scalability
Resources can increase or decrease according to demand.
Access from Different Locations
Authorised users can access services from multiple devices and locations.
Faster Deployment
New servers and applications can often be created quickly.
Collaboration
Several users can work on shared files and systems.
Backup and Recovery Options
Cloud services may provide automated backups, replication and recovery features.
Provider-Managed Infrastructure
The provider manages physical servers, electricity, cooling and some security controls.
Limitations and Risks
Internet Dependency
Some cloud services cannot be accessed when the network connection fails.
Downtime
Cloud services can experience outages. No service should be treated as impossible to fail.
Security Misconfiguration
Incorrect permissions may expose sensitive data.
Ongoing Costs
Pay-as-you-go services can become expensive if usage is not monitored.
Vendor Lock-In
Moving an application or large amount of data to another provider may be difficult or costly.
Privacy and Compliance
Organisations must understand:
- Where data is stored
- Who can access it
- Which laws apply
- How long data is retained
- How data is deleted
Limited Control
Customers do not normally control the provider’s physical infrastructure.
The Shared Responsibility Model
Cloud security is shared between the provider and customer.
The provider may protect:
- Physical data centres
- Physical servers
- Core networking
- Some managed services
The customer may remain responsible for:
- User accounts
- Passwords
- Access permissions
- Stored data
- Application settings
- Some software updates
- Backups
- Security configurations
The exact division depends on whether the service is IaaS, PaaS or SaaS.
CISA’s Cloud Security Technical Reference Architecture includes guidance on shared cloud risks and cloud-security responsibilities.
Important: Moving data to the cloud does not transfer every security responsibility to the provider.
Basic Cloud Security Practices
Use Multi-Factor Authentication
Multi-factor authentication requires more than a password.
For example:
- Password
- Authentication application code
- Physical security key
Apply Least Privilege
Users should receive only the access needed for their work.
A person who only needs to read a document should not automatically receive permission to delete it.
Encrypt Sensitive Data
Encryption protects data while:
- Stored in the cloud
- Transmitted across a network
Encryption keys must also be protected.
Create Backups
Cloud synchronisation is not always a complete backup. Deleted or corrupted files may synchronise across devices.
Keep a separate recovery copy of important data.
Monitor Activity
Logging and monitoring can help detect:
- Unusual logins
- Large downloads
- Permission changes
- Failed access attempts
- Unexpected system activity
Install Updates
Cloud applications, virtual machines and connected devices must be kept updated according to the shared-responsibility model.
Review Sharing Permissions
Remove:
- Public links that are no longer needed
- Old user accounts
- Unnecessary administrator access
- Permissions for completed projects
Cloud Computing Use Cases
Website Hosting
A website can use cloud servers, databases and storage.
Online Education
Cloud platforms can provide:
- Learning materials
- Video classes
- Assignments
- Student accounts
- Online collaboration
Healthcare
Healthcare organisations may use secure cloud systems for authorised records, communication and data analysis.
Business
Businesses use cloud services for:
- Customer management
- Accounting
- File sharing
- Data analytics
- Backup
Artificial Intelligence
Cloud providers offer processing power and tools for training and running AI systems.
Software Development
Developers use cloud environments to build, test and deploy applications.
Real-Life Example: An Online Shop
Imagine an online shop running on cloud services.
The shop uses:
- Cloud storage for product images
- Virtual servers for the website
- A managed database for customer orders
- Automatic scaling during sales
- Cloud backup for recovery
- Monitoring tools for errors
During a major sale, visitor numbers suddenly increase.
The cloud system adds more computing resources. After the sale, those resources are reduced.
This is an example of rapid elasticity.
Cloud Computing vs Traditional Computing
| Traditional Computing | Cloud Computing |
|---|---|
| Organisation buys hardware | Resources are rented or consumed as a service |
| Capacity is planned in advance | Capacity can change quickly |
| Large initial cost | Often usage-based cost |
| Organisation maintains hardware | Provider maintains physical infrastructure |
| Local access may continue offline | Internet or network access is often required |
| Physical control is greater | Provider dependency is greater |
Cloud Computing vs Edge Computing
Cloud computing processes data in remote data centres.
Edge computing processes data closer to where it is created.
| Cloud Computing | Edge Computing |
|---|---|
| Remote processing | Nearby processing |
| Large computing capacity | Faster local response |
| Internet connection often required | Can reduce network dependency |
| Suitable for large-scale storage | Suitable for time-sensitive tasks |
Many modern systems combine both.
For example, a smart camera may detect movement locally using edge computing while storing selected recordings in the cloud.
Common Cloud Computing Myths
Myth: The cloud is a physical cloud in the sky
Fact: Cloud services run on real servers inside data centres.
Myth: Cloud providers handle all security
Fact: Security responsibilities are shared between the provider and customer.
Myth: Cloud storage is automatically a complete backup
Fact: Synchronised deletion or corruption may affect cloud files. Separate backups are still important.
Myth: Cloud computing is always cheaper
Fact: It can reduce initial costs, but unmanaged usage may create unexpectedly high bills.
Myth: Cloud services never fail
Fact: Cloud providers can experience outages. Important services need recovery plans.
How to Choose a Cloud Service
Before selecting a service, consider:
- Required storage and computing power
- Security features
- Data location
- Backup and recovery
- Provider reliability
- Compatibility
- Cost
- Technical support
- Ability to move data
- Legal requirements
- User permissions
Do not select a cloud service based only on the lowest price.
Skills Used in Cloud Computing
Cloud careers may require knowledge of:
- Computer networks
- Operating systems
- Virtualisation
- Databases
- Cybersecurity
- Programming
- Containers
- Backup and recovery
- Identity management
- Cost management
Beginners should start with networking, operating systems and basic cybersecurity.
Quick Cloud Safety Checklist
- Use strong passwords
- Enable multi-factor authentication
- Review sharing permissions
- Keep separate backups
- Encrypt sensitive data
- Remove unused accounts
- Monitor unusual activity
- Understand the service agreement
- Check data location and retention
- Track usage and costs
Conclusion
Cloud computing provides storage, applications, servers and other computing resources through a network. Its main service models are IaaS, PaaS and SaaS, while common deployment models include public, private and hybrid cloud.
Cloud computing can provide flexibility, scalability and faster deployment. However, users must manage accounts, permissions, data, costs and backups carefully.
Remember: The cloud is someone else’s computing infrastructure—not a place where security and responsibility disappear.
Frequently Asked Questions
What is cloud computing in simple words?
Cloud computing means using storage, applications, servers or other computing resources through the internet instead of managing everything on one local computer.
What are IaaS, PaaS and SaaS?
IaaS provides infrastructure, PaaS provides an application-development platform and SaaS provides a complete application.
Is cloud computing the same as cloud storage?
No. Cloud storage is one cloud service, while cloud computing also includes servers, applications, databases, networking and processing power.
Is cloud computing safe?
It can be secure when providers and customers correctly manage encryption, access, updates, monitoring and backups.
Does cloud computing require internet access?
Most cloud services require a network connection, although some applications may provide limited offline features.
Who owns data stored in the cloud?
Ownership depends on the user agreement and applicable law. Users should review the provider’s terms, privacy policy and data-retention rules.
