Good Regexp tutorial with the notes.

Happy 2016 New Year to everyone! Start this year with basics everyone should know!

All the chapters you can read here: http://regexone.com

Lesson Notes:

    abc…    Letters
    123…    Digits
    \d	    Any Digit
    \D	    Any Non-digit character
    .	    Any Character
    \.	    Period
    [abc]   Only a, b, or c
    [^abc]  Not a, b, nor c
    [a-z]   Characters a to z
    [0-9]   Numbers 0 to 9
    \w	    Any Alphanumeric character
    \W	    Any Non-alphanumeric character
    {m}	m   Repetitions
    {m,n}   m to n Repetitions
    *	    Zero or more repetitions
    +	    One or more repetitions
    ?	    Optional character
    \s	    Any Whitespace
    \S	    Any Non-whitespace character
    ^…$	    Starts and ends
    (…)	    Capture Group
    (a(bc)) Capture Sub-group
    (.*)    Capture all
    (abc|def)   Matches abc or def