With the exception of top of the line tournament style paintball marker, most paintball guns are semi-automatic.  This means one ball comes out per trigger pull.  It also means your gun will shoot as fast as you can pull the trigger!  In case semi-automatic isn't fast enough for you, more trigger options are available as an upgrade for most paintball guns; these are called electronic triggers.  Most e-triggers offer at least 3 firing options, semi-automatic, 3 round burst and fully automatic.  Electronic triggers are generally fairly simple to install and cost between $80-$125.  With a price tag that high, the question should be asked before buying... 'how necessary is na e-trigger?'.

If you're new to paintball, you'll be surprised how fast even the cheapest paintball markers shoot.  For most players, semi-automatic paintball guns shoot plenty fast enough; yet fully automatic action still finds it's place on the paintball field.  The rrecent popularity of tactical scenario paintball has brought super realistic military replica gear to the game.  Tactical paintball markers (like the T68 Gen6) are being made to mimic real machine guns and assault rifles to a 'T".  Electronic triggers that offer fully automatic firing definitely adds to their realism. 

One consideration to make before upgrading your paintball marker with an e-trigger is the cost of paint.  Paintballs are expensive!  It's very easy to waste a lot of paint with a fully automatic paintball gun.  One the other hand, remember elecetronic triggers come with 3 options - semi, 3 round burst and full auto.  The best advice is to use semi-auto and 3 round burst most of the time to save paint.  You may not need it, but fully automatic firing would be great to have when you want it in a pinch.