A delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data streams.An example of a delimiter is the comma character, which acts as a field delimiter in a sequence of comma-separated values.

Delimiters represent one of various means to specify boundaries in a data stream. Declarative notation, for example, is an alternate method that uses a length field at the start of a data stream to specify the number of characters that the data stream contains.