In the context of computing and technology, semantics means the use of domain knowledge to make software more intelligent, adaptive, and efficient.
By using knowledge specific to applications, one can enhance their functionalities and optimize the performance. Often combined with some reasoning capabilities, the use of domain knowledge enables software to do useful tricks such as finding hidden relationships in a complicated web of objects.

The latest incarnation of semantics in computing is centered around ontology. An ontology characterizes the intended meaning of terms by formally defining relations among terms in a domain. Founded on a powerful and expressive logic (known as description logic), the modern ontology technology enables one to specify useful domain knowledge and externalize it from software.
In addition to all these benefits of using semantics, the externalization of ontology improves knowledge sharing and reuse and makes software adaptable to environment.

There are a number of problems semantics solves particularly well, such as problems with information integration, model transformation, translation, data cleansing, search, navigation, text understanding, document preparation, and speech understanding. Semantics technology can help developers working in such areas across numerous industries.

The Semantic Web is a "man-made woven web of data" that facilitates machines to understand the semantics, or meaning, of information on the World Wide Web.
The concept of Semantic Web applies methods beyond linear presentation of information (Web 1.0) and multi-linear presentation of information (Web 2.0) to make use of hyper-structures leading to entities of hypertext.