Suggest an editImprove this articleRefine the answer for “What is a loop in a graph?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)A **loop** is an **edge that connects a vertex to itself**. **Key point:** a loop is an edge that starts and ends at the same vertex.Shown above the full answer for quick recall.Answer (EN)ImageA **loop** is an **edge that connects a vertex to itself**. Formally: If an edge connects a vertex **v** to itself, it is a loop: **(v, v)**. --- ### Example If a graph has a vertex **A**, and an edge goes from **A → A**, that is a loop, the vertex "refers" to itself. --- ### Features - A loop can occur in both **directed** and **undirected** graphs. - It **increases the degree of the vertex**: in an undirected graph, a loop adds **2** to the degree, in a directed graph, **1** to the in-degree and **1** to the out-degree. --- ### Interpretation - In a social network, a user interacts with themselves. - In automata, a state from which the system can remain in the same state. --- **Summary:** a loop is an edge that starts and ends at the same vertex.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.