There are 6 tab lines representing 6 strings on the guitar. (The 1st string is the thinnest, and the 6th string is the thickest).

E----------------------------- String 1 Thinnest
B----------------------------- String 2
G----------------------------- String 3
D----------------------------- String 4
A----------------------------- String 5
E----------------------------- String 6 Thickest

• The string at the top is the thickest - 6th string
• The string at the bottom is the thinnest - 1st string (as shown in diagram below)

When a number is placed on one of the lines, it indicates the fret location of note.

Example 1:

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)

Example 2:

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)

Example 3:

E----------------------------- String 1
B-----------6----------------- String 2
G-------5--------------------- String 3
D----------------0------------ String 4
A----------------------------- String 5
E----------------------------- String 6

This indicates:
5th Fret, 3rd string, then
6th Fret, 2nd string, then
an open 4th string.

Example 4:

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.