Topology
Topology is a branch of mathematics that studies how geometric properties are preserved throughout continuous deformations. Continuous deformations are things such as stretching, bending, and twisting; they are not deformations such as gluing and cutting.
One of the first terms necessary to understanding topology is a set. A set is an object that consists of defined and distinct objects. That is to say that elements of a set are different from each other. Since a set is an object and it is made of objects, a set may consist of other sets. Important concepts associated with sets include open sets, closed sets, and bounded sets. The important distinction in topology between open and closed sets is that a closed set includes all of its limit points whereas an open set does not. Limit points are those such that a limit point P of set S is such that every possible open set around P contains at least one other point of S. A set is bounded essentially if it is of finite size. For a set to be bounded, there must be a corresponding metric to the set.
Another fundamental term for understanding topology is neighborhood. This can largely be understood using the common knowledge of what a neighborhood is. In terms of topology, a neighborhood of a point P is a set of points that contains P in which you can move in a small amount in any direction and not leave the set. That is to say, a neighborhood of a point is an area around a point that is within the larger set.
The next topic to understand in topology is that of a topological space. In a general understanding, a topological space is a set of points and a corresponding set of neighborhoods. A topological space also must satisfy a set of axioms (conditions) that relate the points and the neighborhoods.
