Introduction to Online Social Networks

What is a Social Network?

A social network is a group of people who are connected with each other.

• People connect by:

  • Friendship

  • Family

  • Work

  • Common interests

Real-life example

• Your college classmates form a social network.

• Your family WhatsApp group is also a social network.

Why Social Networks Matter

• Humans like to:

  • Talk

  • Share

  • Help each other

• Social networks make communication easy and fast.

Example

• You share exam notes with friends.

• You ask doubts in a class group.

From Offline to Online Communities

1. Offline Communities

Offline communities exist without the internet.

• Examples:

  • School classrooms

  • Villages

  • Offices

  • Sports teams

Problems

• Limited reach

• Slow communication

• Physical presence needed

2. Online Communities

Online communities exist on the internet.

• Examples:

  • Facebook groups

  • WhatsApp groups

  • Telegram channels

  • Reddit communities

Benefits

• Connect anytime

• Connect from anywhere

• A large number of people

Example

• Online coding groups help students learn from home.

Comparison Table: Offline vs Online Communities

Feature	Offline	Online
Location	Same place	Anywhere
Speed	Slow	Fast
Reach	Limited	Very large
Cost	High	Low

Online Social Networks (OSNs)

What are Online Social Networks?

Online Social Networks are websites or apps where people:

• Create profiles

• Connect with others

• Share content

Examples

• Facebook

• Instagram

• Twitter (X)

• LinkedIn

Common Features of OSNs

• User profile

• Friends or followers

• Likes, comments, shares

• Messages

College example

• Students share events on Instagram.

• Teachers post updates in WhatsApp groups.

Evolution of Online Social Networks

Early Stage

• Simple websites

• Text-based chatting

Example

• Orkut

• Yahoo Chat

Growth Stage

• Photos and videos added

• Better design

Example

• Facebook

• YouTube

Modern Stage

• Mobile apps

• Live streaming

• AI suggestions

Example

• Instagram Reels

• YouTube Shorts

Memory Tip

📌 Text → Photo → Video → Live → AI

Analysis and Properties of Online Social Networks

Network Structure

OSN looks like a graph.

• Nodes = Users

• Links = Friend connections

Simple diagram

User A ---- User B ---- User C

Key Properties

Degree

• The number of friends a user has
  Example: A popular student has many connections.

Centrality

• Important users in the network
  Example: Class representative

Clustering

• Small groups inside big networks
  Example: Department-wise groups

Why Analysis Matters

• Find popular users

• Show relevant ads

• Detect fake accounts

Security Issues in Online Social Networks

What is Security?

Security means keeping data safe.

Common Security Problems

• Fake profiles

• Account hacking

• Data leaks

• Online fraud

Example

• Fake Instagram accounts asking for money.

Why Security is Important

• Protect personal data

• Avoid financial loss

• Stay safe online

Trust Management in Online Social Networks

What is Trust?

Trust means believing someone is real and safe.

How Trust Works Online

• Verified accounts

• Mutual friends

• Profile history

Example

• You trust a senior student more than a random stranger.

Trust Management Techniques

• Blue tick verification

• Report/block options

• Friend request limits

Controlled Information Sharing

What is Information Sharing?

Sharing photos, videos, and details online.

Controlled Sharing

Users decide:

• Who can see posts

• What data is shared

Example

• Private Instagram account

• WhatsApp “Only contacts” setting

Why Control is Needed

• Privacy protection

• Avoid misuse

Identity Management in Online Social Networks

What is Identity?

Your online identity is how you appear online.

• Name

• Photo

• Bio

• Posts

Identity Problems

• Fake identity

• Identity theft

Example

• Someone using your photo to create a fake account.

Identity Management Solutions

• Strong passwords

• Two-factor authentication

• Profile verification

Data Collection from Social Networks

What is Data Collection?

Collecting information from social media.

• Likes

• Comments

• Posts

• Followers

Why Data is Collected

• Research

• Marketing

• Trend analysis

Example

• Companies study product reviews on Instagram.

APIs in Online Social Networks

What is an API?

API (Application Programming Interface)
It allows apps to talk to each other.

Example of API Use

• Login with Google

• Fetch tweets from Twitter

Simple example

• Shopping apps using Google login.

Benefits of APIs

• Easy data access

• Saves time

• Secure communication

Challenges, Opportunities, and Pitfalls

Challenges

• Privacy issues

• Fake news

• Cyber bullying

Opportunities

• Online business

• Learning platforms

• Career networking

Example

• LinkedIn for jobs

Pitfalls (Risks)

• Addiction

• Mental stress

• Data misuse

Collecting Data from Online Social Media

Methods

• APIs

• Web scraping

• Surveys

Issues in Data Collection

• Privacy laws

• Data accuracy

Key Takeaways 

• Social networks connect people.

• Online networks are fast and global.

• Security and privacy are very important.

• APIs help in data sharing.

• Trust and identity keep users safe.

Memory Shortcuts 🧠

• OSN = People + Internet

• API = App to App Talk

• Security = Data Safety

• Trust = Safe Connections

Final Quick Summary

• Offline groups moved to online platforms.

• Online social networks changed communication.

• Data, trust, security, and identity are core topics.

• Social networks offer growth but need careful use.