| Symbol(s) | Meaning | Example | Example Matches |
| * | Matches the preceding character, subexpression, or bracketed character, 0 or more times | a*b* | aaaaaaaa, aaaaabbbb, bbbbbbb |
| + | Matches the preceding character, subexpression, or bracketed character, 1 or more times | a+b+ | aaaaaab, aaaabbbbb, abbbbbbb |
| [] | Matches any character within the brackets (i.e., “Pick any one of these things”) | [A-Z]* | APPLE, CAPITALS, QWERTY |
| {m, n} | Matches the preceding characher, subexpression, or bracketed character between m and n times (inclusive) | a{2,3}b{2,3} | aabbb, aaabbb, aabb |
| [^] | Matches any single character that is not in the brackets | [^A-Z]* | apple, lowercase, qwerty |
| | | Matches any character, string of characters, or subexpression, separated by the “|” (Note that this is a vertical bar, or “pipe”, not a capital “I”) | b(a|i|e)d | bad, bid, bed |
| . | Matches any single character (including symbols, numbers, a space, etc.) | b.d | bad, bzd, b$d, b d |
| ^ | Indicates that a character or subexpression occurs at the beginning of a string | ^a | apple, asdf, a |
| \ | An escape character (this allows you to use “special” characters as their literal meaning) | .\|\ | .|\ |
| $ | Often used at the end of a regular expression, it means “match this up to the end of the string.” Without it, every regular expression has a defacto “.*” at the end of it, accepting strings where only the first part of the string matches. This can be thought of as analogous to ^ symbol | [A-Z]*[a-z]*$ | ABCabc, zzzyx, Bob |
| ?! | “Does not contain.” This odd pairing of symbols, immediately preceding a character (or regular expression), indicates that that character should not be found in that specific place in the larger string. This can be tricky to use; after all, the character might be found in a different part of the string. If trying to eliminate a character entirely, use in conjunction with a ^ and $ at either end | ^((?![A-Z]).)*$ | no-caps-here, $ymb0ls a4e f!ne |
