# DSE Graph Terminology

Explain terminology specific to DSE Graph.

- adjacency list
- A collection of unordered lists used to represent a finite graph. Each list describes the set of neighbors of a vertex in the graph.
- adjacent vertex
- A vertex directly attached to another vertex by an edge.
- directed graph
- A set of vertices and a set of arcs (ordered pairs of vertices). In DSE Graph, the terminology "arcs" is not used, and edges are directional.
- edge
- A connection between vertices. Edges can be unordered (no directional orientation) or ordered (directional). An edge can also be described as an object that has a vertex at its tail and head.
- element
- An element is a vertex, edge, or property.
- global index
- An index structure over the entire graph.
- graph
- A collection of vertices and edges.
- graph degree
- The largest vertex degree of the graph.
- graph partitioning
- A process that consists of dividing a graph into components, such that the components are of about the same size and there are few connections between the components.
- graph traversal
- An algorithmic walk across the elements of a graph according to the referential structure explicit within the graph data structure.
- incident edge
- An edge incident to a particular vertex, meaning that the edge and vertex touch.
- index
- An index is a data structure that allows for the fast retrieval of elements by a particular key-value pair.
- meta-property
- A property that describes some attribute of another property.
- order
- The magnitude of the number of edges to the number of vertices.
- partitioned vertex
- Used for vertices that have a very large number of edges, a partitioned vertex
consists of a portion of a vertex's data that results from dividing the vertex into
smaller components for graph database storage.
*Experimental* - property
- A key-value pair that describes some attribute of either a vertex or an edge. Property key is used to describe the key in the key-value pair. All properties are global in DSE Graph, meaning that a property can be used for any vertices. For example, "name" can be used for all vertices in a graph.
- traversal source
- A domain specific language (DSL) that specifies the traversal methods used by a traversal.
- undirected graph
- A set of vertices and a set of edges (unordered pairs of vertices).
- vertex-centric index
- A local index structure built per vertex.
- vertex
- A vertex is the fundamental unit of which graphs are formed. A vertex can also be described as an object that has incoming and outgoing edges.
- vertex degree
- The number of edges incident to a vertex.