Graphs consists of Nodes (Vertices) that are connected to each other using Edges
Directed and Undirected Graphs
Weighted and Unweighted Graphs
Cyclic and Acyclic Graphs

Graph can be represented using Edge List, Adjacency List and Adjacency Matrix

Uses

Social Media Connections
Recommendation System
Navigation System

Graph Data Structures (Adjacency Matrix, Adjacency List, Edge List) - VisuAlgo