There are 6 tab lines representing 6 strings on the guitar. (The 1st string is the thinnest, and the 6th string is the thickest) They are as follows:
E-----------------------------String 1 B----------------------------- String 2 G----------------------------- String 3 D----------------------------- String 4 A----------------------------- String 5 E----------------------------- String 6 |
When a number is placed on one of the lines, it indicates the fret location of note for example,
E-----------------------------String 1 B------4---------------------- String 2 G----------------------------- String 3 D----------------------------- String 4 A----------------------------- String 5 E----------------------------- String 6 |
This means to play the 4th Fret on the 2nd string
E-----------------------------String 1 B----------------------------- String 2 G----------------------------- String 3 D----------------------------- String 4 A------0---------------------- String 5 E----------------------------- String 6 |
This indicates an open 5th string
E---1-------------------------String 1 B-----------8----------------- String 2 G-------7--------------------- String 3 D---------------2------------- String 4 A----------------------------- String 5 E------------------------12--- String 6 |
This indicates:
1st Fret, 1st string then
7th Fret, 3rd string, then
8th Fret, 2nd string, then
2nd Fret, 4th string, then
12th Fret, 6th string.
Further Points To Remember...
 | Other letters / symbols used in tabs. |
h - hammer on
p - pull off
b - bend string up
r - release bend
/ - slide up
\ - slide down
v - vibrato (sometimes written as ~)
t - right hand tap
x - play 'note' with heavy damping
 | When you see all numbers in a line one after another |
E---3-------------------------String 1 B---3------------------------- String 2 G---4------------------------- String 3 D---5------------------------- String 4 A---5------------------------- String 5 E---3------------------------- String 6 |
...it means you play the entire chord using all strings
 | When you see tabs that have "h" |
E--------------------------------String 1 B--------------------------------String 2 G--------------------------------String 3 D--------------------------------String 4 A---------7h9-----------10h12----String 5 E---0--0----------0--0-----------String 6 |
....it means to do a "Hammer On" from the 7th fret to the 9th fret and again for the 10th fret to the 12th fret
 | When you see other tabs that have "p" |
E--------------------------------String 1 B--------------------------------String 2 G--------------------------------String 3 D--------------------------------String 4 A---------9p7-----------12p10----String 5 E---0--0----------0--0-----------String 6 |
....it means to do a "Pull Off" from the 9th fret to the 7th fret and again for the 12th fret to the 10th fret
 | When you see other tabs that have "b" |
E--------------------------------String 1 B--------------------------------String 2 G--------------------------------String 3 D--------------------------------String 4 A---------7b9-----------10b12----String 5 E--------------------------------String 6 |
...it means strike the string 5 on the 7th fret, then bend the note up so that it sounds the same as the note played on the 9th fret.
Here's a quick tablature legend to keep on file...
| |
h - hammer-on p - pull-off b - bend pb - pre-bend r - bend release (release immediately if no number after r) /\ - slide into or out of (from/to "nowhere") s - legato slide S - shift slide <n> - natural harmonic [n] - artificial harmonic n(n) - tapped harmonic ~ - vibrato tr - trill T - tap TP - trem. picking PM - palm muting \n/ - tremolo bar dip; n = amount to dip \n - tremolo bar down n/ - tremolo bar up /n\ - tremolo bar inverted dip = - hold bend; also acts as connecting device for hammers/pulls <> - volume swell (louder/softer) x - on rhythm slash represents muted slash o - on rhythm slash represents single note slash | |