What is a graph data structure and what are its components?

A graph is a non-linear data structure consisting of vertices (nodes) and edges that connect pairs of vertices. Graphs can be directed (edges have direction) or undirected, weighted (edges have values) or unweighted. Components include vertices (V), edges (E), and optionally weights. Graphs represent relationships like social networks, maps, and dependencies, with common representations being adjacency matrix and adjacency list.