In computing, a delimiter is a character or a sequence of characters for specifying the boundary between separate, independent regions in data such as a text file or data stream. For context, data boundaries can be indicated via other means. For example, declarative notation indicates the length of a field at the start of the field instead of relying on delimiters.

In mathematics, delimiters are often used to specify the scope of an operation in an expression, and can occur both as isolated symbols (e.g., colon in "${\displaystyle 1:4}$") and as a pair of opposing-looking symbols (e.g., angled brackets in ${\displaystyle \langle a,b\rangle }$).

Delimiters are used for a wide range of purposes. The following examples demonstrate a small fraction of their applicability.

Tabular data, organized as rows and columns, is often delimited. A field delimiter separates the columns of a row, with each column corresponding to a field in that row, and a record delimiter separates the rows, with each row corresponding to a record. The commonly used comma-separated values (CSV) format uses a comma to delimit fields, and an newline to delimit records. The following CSV data represents three records each with four fields. The first line is metadata that names the fields.

CSV data is an example of flat-file database.

Source:

Bracket delimiters, also called block delimiters, region delimiters, or balanced delimiters, mark the start and end of a region of text. Commonly used bracket delimiters include:

Delimiter collision describes a limitation of using delimiters. When content information contains a delimiter, then the processing of the data will fail since the embedded delimiter will be incorrectly interpreted as a data boundary unless provisions are made to prevent the collision. In XML, for example, collision can occur when content contains an angle bracket (< or >).