Guitar tabs are an essential part of any learning process, and if you don't know how to read them then it makes life a bit difficult!
Don't be baffled, it's stupidly easy. All you have to be able to do is... well… read! Basically, the fretboard is represented by lines each corresponding to a string, from high to low, like this –

If you were to lay the guitar down on your lap, strings facing up, neck to the left of you, bridge to the right, this is how it's represented.

So, knowing this, we can now start to form the content. Taking our template once again, this time i'll draw up the Gmaj chord.

The notes are overlapped at the same interval, meaning they are played at the same time, thus forming the chord of Gmaj.

Now, I'll draw up the Em scale in tab form, and show how notes that are played singularly are represented.

Non of these notes are at the same interval meaning you should play them singularly, note by note.

 

Symbols

Accompanying tabs are many key symbols. Unlike sheet music, tab is more universally understood and easier to read, however it's not quite so in depth when it comes to showing time signatures, note durations, rests, and other musical features.
That said, tab does have quite a versatile key of symbols that it utilises, and I'll show a few of them here. You'll find these under, or sometimes above the note that they affect.

 

Palm Muting 

 

 

Palm Muting is illustrated by the initials ‘P.M’ here, and any note(s) that require this technique after the first one are represented by the “--|”.

 

 

Slides

 

 

This ‘sl’ with a slanted line between the notes represents a slide, where you fret the first note (in this case the 5^th fret on the A string) and pick it, then without striking the string again you simply keep your finger on the fretboard and slide up to the next note (7^th fret).

 

 

Hammer-ons/Pull-offs

 

 

Hammer-ons and Pull-offs. The ‘H’ between notes shows you should hammer on to the next note, the ‘P’ showing a pull-off. Often, if it’s just a single action, it will just show the H or the P between the two notes.

 

 

Two-hand Tapping

 

 

Tapping. The note that is to be tapped (with a finger from your picking hand) is marked by the ‘T’.

 

 

Up/Down Strokes

 

Up/Down Strokes are represented by the directional markings underneath each note.

 

 

Harmonics

 

A.H above a note shows it’s an artificial harmonic. This is sometimes a more specific indication shown with a P.H to show it’s a ‘pinched harmonic’ and is also sometimes shown with the note affected in a triangle. N.H on a note/group of notes shows a natural harmonic, where you rest your finger on the string above the fret, without pushing down, and pick.