Tokenization

Last Updated: November 19, 2012

Definition - What does Tokenization mean?

Tokenization is the act of breaking up a sequence of strings into pieces such as words, keywords, phrases, symbols and other elements called tokens. Tokens can be individual words, phrases or even whole sentences. In the process of tokenization, some characters like punctuation marks are discarded. The tokens become the input for another process like parsing and text mining.

Tokenization is used in computer science, where it plays a large part in the process of lexical analysis.

Techopedia explains Tokenization

Tokenization relies mostly on simple heuristics in order to separate tokens by following a few steps:

Tokens or words are separated by whitespace, punctuation marks or line breaks
White space or punctuation marks may or may not be included depending on the need
All characters within contiguous strings are part of the token. Tokens can be made up of all alpha characters, alphanumeric characters or numeric characters only.

Tokens themselves can also be separators. For example, in most programming languages, identifiers can be placed together with arithmetic operators without white spaces. Although it seems that this would appear as a single word or token, the grammar of the language actually considers the mathematical operator (a token) as a separator, so even when multiple tokens are bunched up together, they can still be separated via the mathematical operator.