Gremlin is a domain specific language for traversing graphs. Graphs are data structures where there exists vertices (i.e. dots, nodes) and edges (i.e. lines, arcs). Gremlin was designed to work with a type of graph called a property graph. Property graphs are defined, in detail, in the Defining a Property Graph section of this documentation. By using Gremlin, it is possible make use of a REPL (command line/console) to interactively traverse a graph.