Graphs
They are ways to represent data, like linked lists or arrays, but they differ in that they are non-linear, meaning they don’t have a single way to traverse them(somewhat similar to trees), those nodes (or vertices) are then connected by what’s called “edges”.
Depending on the graph type, those edges could also carry some data, most notably “weight”, which are numerical values that represent an edges “weight” between two vertices, i.e. how strong their connection is (by whatever scale the business is using).