DelimiterAutoMatching

is an option for cells and notebooks that specifies whether matching delimiters are automatically inserted when typing Wolfram Language code.

Details

DelimiterAutoMatchingTrue causes the typing of certain open delimiters to automatically insert the corresponding closing delimiter after the text caret in affected cells. This setting also causes the typing of a closing delimiter to type through an existing closing delimiter as if you had pressed the right arrow key.
Delimiter auto-matching is turned on by default in the Input and Code styles. The option may be toggled globally from the Interface pane of the Preferences dialog.
The supported open delimiters and the matched closing delimiters include:

DelimiterAutoMatching is only effective in BoxData cells.
DelimiterAutoMatching uses heuristics to determine whether it would make sense to auto-match a delimiter in a given context. The heuristics used include:

	Never auto-match inside of a string.
	Never auto-match if it appears that you are trying to wrap delimiters around an expression.
	Never auto-match or type through if all delimiters in the cell are not matched.

Typing into the cell demonstrates the auto-matching behavior:

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