Guitar tablature (TAB for short) is a method of notation that makes it easy for musicians to exchange music with a standard computer by graphically representing the strings and frets on a guitar fretboard. Numbers are placed on respective lines which indicate the fret to play and on which string to play it. With these instructions you will be able to understand how to read and write guitar TAB quickly.
TABs are written in lines. Each line represents a string on the guitar. The thickest string being the bottom most line and the thinnest string being the topmost. Picture yourself looking at the strings/fretboard as you are holding the guitar to play. The first string is the low 'E' string and is represented by the bottom line on the TAB. The last string, is the high 'E' and is represented by the top line of the TAB.