How to Play Trills on an Electric Guitar

A trill is a fast alternation of two notes.

For example in the video below I alternately play the note C at the 8th fret and the note D at the 10th fret, both on the 1st string:

The easiest way to perform trills on an electric guitar is by using hammer on and pull off legato technique.

Performing explanation:

I play the 1st note by stroking the 1st string at the 8th fret with the pick (alternatively a trill could also be started with a hammer on or pull off from any other note).

Next I perform a hammer on at the 10th fret,and take a pull off back at the 8th fret.

After that I again play the hammer on and again the pull off, and so on.

Start off by playing this circle slowly while watching that every step you make is in an accurate manner, once you can play it consistently, begin increasing the speed.

Because the notes within the loop are played only with the fretting hand, it's much more easier to achieve greater speeds spending less time.

In printed guitar tabs a trill has the following notation:

Guitar trill notation used in guitar tablatures
the number in the brackets tells about the position of the 2nd alternate note.

In plain text tabs it can also be marked as the "tr" letters between fret numbers:

1|----------------
2|-----7tr8-------
3|----------------
4|----------------
5|----------------
6|----------------

Another, more unusual way of performing trills on an electric guitar is to use the side of the plectrum for tapping the 2nd note, you can see how it can be done here.