What is Vocabulary Control?

Vocabulary Control encloses to the process of maintaining, and using a controlled vocabulary, where a limited set of terms must be used to index documents, and to search for these documents, in a particular system. It is defined as a list of terms showing their relationships and used to represent the specific subject of the document. A certain structure is given to the terms,and those are limited in controlled Vocabulary. But in an uncontrolled vocabulary set of terms are unlimited because of natural language.