Watch the Palm Muting online guitar lesson by Chris Buono from 60 Electric Guitar Techniques You MUST Know
Placing the back end of your pick hand palm on the bridge saddle where the strings sit will produce a chunky, punchy attack known as palm muting. Don't let the "muting" part of the name throw you off - you're not muffling notes, you're simply changing their character and providing a thickness to the mix that only the electric guitar can provide. Six-stringers unite!
Looking for inspiration? If you listen to metal, then just take your pick. The same goes for just about any other electric guitar-based music, but if you want a specific defining moment, a tip of the hat goes to Mike Campbell of the Heartbreakers in "I Won't Back Down" or Jimmy Page in "Communication Breakdown".