Dropping your opponent

Dropping your opponent is a great way to do a lot of damage, with little cost to yourself. The basic idea is, that you fly/teleport units into the opponents base, and do as much damage as you can before succumbing to defenses. In a very succesful drop, you actually fly your troops out of the base again before they are destroyed, thus losing no troops while seriously damaging your opponent. Note that the units does not require to be land units. In SC1 a group of scouts, due to their speed, could do wonders on an unprotected worker outpost.

The successfulness of a drop can be measured in how much it costs your opponent (versus your cost of lost troops.) For this, an accurate calculation of how much is lost by losing one worker should be used. See the Mining 101 strategy guide.

However, a hidden cost is also useful when determining the success rate of your latest heavenly strike of worker vengenace. That of yout opponent players time and effort to

a) Rebuild workers - He's gonna need them, and it could just be that little extra distraction your next move requires.
b) Strengthen defenses - Chances are he doesn't want it happening again, and those towers are mighty expensive. Ok, we cant drop there again, but he learned his lesson the HARD way.
c) Vent - a well executed drop is such a humiliating and infuriating thing to suffer, that it might throw your opponent offf balance - even just a little.

In short, the benefits of dropping your opponent are numerous. As always, the economy largely rules the game. Hit your opponents economy, and you've got him by the tail.