A navigation mesh is an abstract data structure

Data structure

In computer science, a data structure is a particular way of storing and organizing data in a computer so that it can be used efficiently.Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks...

 used in artificial intelligence

Artificial intelligence

Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

 applications to aid agent

Intelligent agent

In artificial intelligence, an intelligent agent is an autonomous entity which observes through sensors and acts upon an environment using actuators and directs its activity towards achieving goals . Intelligent agents may also learn or use knowledge to achieve their goals...

s in path-finding

Search algorithm

In computer science, a search algorithm is an algorithm for finding an item with specified properties among a collection of items. The items may be stored individually as records in a database; or may be elements of a search space defined by a mathematical formula or procedure, such as the roots...

 through large spaces. Meshes that do not map to static obstacles in the environment they model offer the additional advantage that agents with access to the mesh will not consider these obstacles in path-finding, reducing computational effort and making collision detection

Collision detection

Collision detection typically refers to the computational problem of detecting the intersection of two or more objects. While the topic is most often associated with its use in video games and other physical simulations, it also has applications in robotics...

 between agents and static obstacles moot. Meshes are typically implemented as graph

Graph (data structure)

In computer science, a graph is an abstract data structure that is meant to implement the graph and hypergraph concepts from mathematics.A graph data structure consists of a finite set of ordered pairs, called edges or arcs, of certain entities called nodes or vertices...

s, opening their use to a large number of algorithms defined on these structures.
One of the most common uses of a Navigation Mesh is in a video game. It is usually represented as a volume or brush that is processed and computed during level compilation.