# Day1 azure # Basics of Cloud Computing ## **What is a Server?** A **server** is just a computer, but instead of being used like your laptop (for browsing, gaming, etc.), it's designed to **run applications and process data** for others. It has a **CPU, RAM, and storage**, but unlike personal computers, it doesn’t need things like a display or a graphics card. For example, Instagram is not stored on your phone. Instead, when you open the app, it **connects to a server** that stores all the data and processes your requests. ### **How Were Servers Managed Before?** About **10 years ago**, big companies like Google and IBM had their own **data centers** (large rooms full of servers). If a developer needed a server, a **system administrator** would manually find a free one and assign it. ### **The Problem with Managing Data Centers** Companies like Google had the money and resources to build huge data centers, but **startups struggled** because: 1. They needed **24/7 electricity** to keep servers running. 2. They had to hire **system admins** to maintain the servers. 3. They had to handle **upgrades, security patches, and monitoring** constantly. 4. It was **expensive** to set up and maintain everything. ### **How AWS Changed Everything** Then **Amazon Web Services (AWS)** came in and said: * "We will build **data centers** all over the world." * "If a company needs 10 servers, they can rent them from us instead of buying and maintaining their own." * "We will take care of electricity, maintenance, security, and updates." This idea became the **Public Cloud**, where companies rent servers instead of owning them. ### **Difference Between Private Cloud & Public Cloud** 1. **Private Cloud** – Companies still **own** and manage their own servers (e.g., banks, financial institutions) because they need high security. 2. **Public Cloud** – Companies **rent** servers from cloud providers like AWS, Azure, or Google Cloud. ### **What is a Hybrid Cloud?** A **Hybrid Cloud** is a mix of both. For example, a company might: * Use **AWS or Azure** for general applications. * Keep **sensitive data** (like customer details) on **their own private servers** for security reasons. ### **What is Multi-Cloud?** Multi-cloud means using **multiple cloud providers** at the same time. For example: * A company might use **AWS** for databases. * Use **Azure** for AI/ML services. This helps businesses avoid depending on just one cloud provider. **What is Cloud?** Think of the **cloud** as a huge, virtual storage space and computer that you can access through the internet. Imagine you have a phone or laptop, but instead of saving everything on your device, you store your files, photos, and apps in a **big, secure computer (server)** located somewhere else. You can access your data **anytime, from anywhere, as long as you have an internet connection**. For example: * **Google Drive** – You don’t need to store files on your computer; they are in the cloud. * **Netflix** – You don’t download movies; you stream them from the cloud. --- ### **What is Cloud Computing?** **Cloud computing** is the **delivery of computing services (like storage, software, and processing power) over the internet** instead of using your own physical computer or servers. In the past, companies had to buy and maintain their own big, expensive computers (called servers). But now, they can just **rent computing power from cloud providers** like **Amazon Web Services (AWS), Microsoft Azure, or Google Cloud**. --- ### **Types of Cloud Computing** There are three main types: 1. **Public Cloud** 2. **Private Cloud** 3. **Hybrid Cloud** #### **1\. Public Cloud** – Shared Digital Space for Everyone * **Who Uses It?** – Individuals, businesses, and organizations. * **How It Works?** – The cloud provider owns the servers, and multiple customers share the resources. * **Example:** * **Google Drive** – Everyone can store files there. * **Amazon Web Services (AWS)** – Many companies rent computing power from AWS. **Think of it like renting an apartment in a big building.** You don’t own the building, but you pay rent to live in one of the apartments. Other people also live in the same building, but they have separate apartments. --- #### **2\. Private Cloud** – Exclusive Digital Space for One Organization * **Who Uses It?** – Large businesses or organizations that want more control over their data. * **How It Works?** – The company owns and maintains its own servers, and only authorized people can access them. * **Example:** * **Banks and government agencies** often use private clouds to keep data extra secure. **Think of it like owning a house.** You don’t share it with anyone else; it’s fully yours. --- #### **3\. Hybrid Cloud** – A Mix of Private and Public Cloud * **Who Uses It?** – Businesses that need both security and flexibility. * **How It Works?** – Some data is stored in a private cloud (for security), while other services run on a public cloud (for scalability and cost savings). * **Example:** * A hospital might store patient records on a **private cloud** (for security) but use a **public cloud** to run an appointment booking system. ## **Think of it like having a house (private) but also renting a storage unit (public) when you need extra space.** **Vocabulary :** **1\. Virtualization** – Creating Virtual Computers Virtualization means making **virtual versions of computers, storage, or networks** instead of using separate physical machines. **Example:** Imagine one big computer being split into **many smaller virtual computers**, each running different programs. --- #### **2\. Virtual Machine (VM)** – A Software Computer A **Virtual Machine (VM)** is like a computer that runs **inside another computer** using software. It allows running multiple operating systems (Windows, Linux) on the same machine. **Example:** You have a Windows computer, but inside it, you run a **virtual Linux computer** without buying a separate machine. --- #### **3\. API (Application Programming Interface)** – A Way for Apps to Talk An **API** is a set of rules that allows different software to **communicate and share data**. **Example:** When you use **Google Maps inside a food delivery app**, the app uses an API to get map data from Google. --- #### **4\. Regions** – Locations of Cloud Data Centers Regions are **different locations worldwide** where cloud companies (AWS, Google Cloud, Azure) have their servers. **Example:** A cloud provider may have data centers in **India, USA, and Europe** so users get fast access based on location. --- #### **5\. Availability Zones** – Backup Inside a Region An **Availability Zone (AZ)** is like a **backup data center** inside a region. It ensures that if one data center fails, another one takes over. **Example:** If one **AWS data center in Mumbai** goes down, another in the same region takes over to keep services running. --- #### **6\. Scalability** – Growing as Needed Scalability means **adding more resources** (servers, storage) when needed **without affecting performance**. **Example:** An online store gets **more visitors** on a sale day, so the cloud automatically adds **more servers** to handle the traffic. --- #### **7\. Elasticity** – Expanding and Shrinking Automatically Elasticity means a system can **increase or decrease resources automatically** based on demand. **Example:** If a website has **low traffic at night**, the cloud **reduces resources** to save money and **expands again in the morning** when traffic increases. --- #### **8\. Agility** – Quick and Flexible Deployment Agility means being **able to make quick changes** and deploy new services faster. **Example:** A company can **quickly create new apps or websites** in the cloud **without buying new servers**. --- #### **9\. High Availability (HA)** – Always Online High availability means a system is **running almost all the time**, with very little downtime (99.9% uptime or more). **Example:** Google Search, Amazon, and Netflix **almost never go offline** because they use cloud systems with high availability. --- #### **10\. Fault Tolerance** – Keep Running Even with Failures Fault tolerance means the system **keeps working** even if some parts fail. **Example:** If **one hard drive crashes**, a backup takes over **so there’s no data loss or downtime**. --- #### **11\. Disaster Recovery** – Getting Systems Back After a Problem Disaster recovery means **having a plan** to restore lost data or bring systems back online after an issue like a cyberattack or earthquake. **Example:** A company keeps **backup data in another city**, so if their main server fails, they can **restore everything from the backup**. --- #### **12\. Load Balancing** – Sharing Work Between Servers Load balancing means **spreading tasks across multiple servers** so no single server gets overloaded. **Example:** If **millions of people** visit an e-commerce website at the same time, a load balancer **divides the traffic** across multiple servers to keep the site fast.