Function: string-match

Return index of start of first match for REGEXP in STRING, or nil.
Matching ignores case if `case-fold-search' is non-nil.
If third arg START is non-nil, start search at that index in STRING.
For index of first char beyond the match, do (match-end 0).
`match-end' and `match-beginning' also give indices of substrings
matched by parenthesis constructs in the pattern.

You can use the function `match-string' to extract the substrings
matched by the parenthesis constructions in REGEXP.
(fn REGEXP STRING &optional START)