Here's some basic stuff:

? - The question mark indicates there is zero or one of the preceding element.

• • The asterisk indicates there are zero or more of the preceding element.
• • The plus sign indicates that there is one or more of the preceding element.
    . - Matches any single character.
    | - Matches either the expression before or the expression after the operator.
    ^ - Matches the starting position within the string.
    $ - Matches the ending position of the string.
    [ ] - Matches a single character that is contained within the brackets. [abc] [a-c]
    [^ ] - Matches a single character that is not contained within the brackets.
    {m,n} - Matches the preceding element at least m and not more than n times. (n optional)

+like

Horizontal scroll doesn't work and you should write as plaintext