🌩️ What Is Cloud Computing?
Cloud computing refers to using computing resources such as servers, storage, databases, networking, and software through the internet instead of owning physical hardware.
Rather than buying and maintaining servers on your own premises, cloud users access resources hosted on remote data centers. These resources are available on demand, and users are charged only for what they actually consume.
In simple words, cloud computing allows applications and data to run on online servers instead of local machines.
⭐ Key Features of Cloud Computing
Scalability
Resources can be increased or reduced easily based on workload.
Elasticity
Systems automatically adjust capacity when demand changes.
High Availability
Services remain accessible with minimal downtime.
Agility
Resources can be provisioned quickly within minutes.
Fault Tolerance
Applications continue working even if a component fails.
Disaster Recovery
Data and applications can be restored after failures or disasters.
Pay-As-You-Go Pricing
Users pay only for the resources they use.
☁️ Cloud Service Models
🔹 Infrastructure as a Service (IaaS)
More control is given to the user
Cloud provider manages hardware and virtualization
User manages OS, applications, and data
Common use cases:
Virtual machines
Testing and development
Application migration
Examples:
AWS EC2
Azure Virtual Machines🔹 Infrastructure as a Service (IaaS)
More control is given to the user
Cloud provider manages hardware and virtualization
User manages OS, applications, and data
Common use cases:
Virtual machines
Testing and development
Application migration
Examples:
AWS EC2
Azure Virtual Machines
🔹 Platform as a Service (PaaS)
Responsibilities are shared
Provider manages OS, runtime, and infrastructure
User focuses only on application code
Ideal for:
Application development
Example:
Heroku
🔹 Software as a Service (SaaS)
Provider manages everything
Users access applications via browser
No installation required
Examples:
Gmail
Outlook
Microsoft 365
OneDrive
🔐 Shared Responsibility Model
The shared responsibility model explains who is responsible for what in cloud security.
Cloud Provider → Infrastructure, physical security, and underlying services
Customer → Data, user access, configurations, and applications
📌 Responsibility depends on whether you use IaaS, PaaS, or SaaS.
🌍 Cloud Deployment Models
Private Cloud
Dedicated environment
High security and control
Higher cost and maintenance
Public Cloud
Fully managed by provider
Cost-effective
No infrastructure management
Hybrid Cloud
Mix of private and public cloud
Sensitive data stays private
Multi-Cloud
Uses multiple cloud providers
Avoids vendor lock-in
🔌 API (Application Programming Interface)
An API is a set of rules that allows software systems to communicate with each other.
In cloud environments, APIs enable users to interact with:
Compute services
Storage
Databases
AI and ML services
📈 Scaling in Cloud Computing
Vertical Scaling
Increasing resource size
Example: Adding more RAM or CPU to a VM
Horizontal Scaling
Adding or removing instances
Common in high-traffic applications
🖥️ Virtualization
Virtualization allows multiple virtual machines to run on a single physical server.
Key benefits:
Better hardware utilization
Multiple OS on one machine
Cost efficiency
⚙️ Hypervisor
A hypervisor is software that:
Creates and manages virtual machines
Isolates multiple VMs on one host
Allows different OS to run simultaneously
📦 Containerization
Containerization is a lightweight alternative to virtualization, mainly used for microservices.
Key points:
Packages application with dependencies
Shares host OS kernel
Faster and lightweight
Solves “it works on my machine” issue
Best for:
Microservices
Scalable backend systems
⚠️ Containers cannot run a different OS kernel.
🏢 Datacenters, Regions & Availability Zones
Datacenter
A physical building that stores servers and networking equipment.
Region
A geographical area containing multiple datacenters.
Availability Zones
Isolated datacenters within a region
Ensure high availability and fault tolerance
🧩 Virtual Machines vs Containers
🖥️ Virtual Machines (VMs)
Each VM runs its own full operating system
Uses a hypervisor on top of physical hardware
More secure but heavier and slower
Requires more CPU, RAM, and storage
Best for:
Legacy applications
Strong isolation requirements
📦 Containers
Share the host operating system kernel
No separate OS for each application
Lightweight and fast
Starts in seconds
Best for:
Microservices architecture
High-scalability applications
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