1. The **order** of a graph is defined as the number of vertices (nodes) it contains. 2. The **size** of a graph is defined as the number of edges (connections) it contains. 3. In general, if a graph $G$ has $n$ vertices and $m$ edges, then: - Order of $G$ is $n$ - Size of $G$ is $m$ 4. For example, if a graph has 5 vertices and 7 edges, its order is 5 and its size is 7. This is a fundamental concept in graph theory used to describe the basic structure of a graph.