A backreference allows a previously matched subexpression to be identified subsequently in the same regular expression. The following table lists the backreference constructs supported by regular expressions in the .NET Framework.
|\ number||Backreference. Matches the value of a numbered subexpression.||(\w)\1||"ee" in "seek"
|\k<name>||Named backreference. Matches the value of a named expression.||(?<char>\w)\k<char>||"ee" in "seek"