First off here is a little general info for you. Cougars and their relatives can be found just about anywhere from the Yukon to the Southern Andes. In the Pacific Northwest males range from 115 to 198 lbs and the females are smaller at 64 to 141 lbs. These feisty felines will literally eat anything with meat on it from moose, elk, and horses down to insects.
Now that we have been briefly acquainted with this beautiful animal, there are a few things you should know to help prevent a cougar from getting acquainted with you. When you are out for a hike it is highly recommended that you go with a least one other person and be aware that cougars are most likely to be hunting at dawn or dusk, although they will hunt and scamper 24/7 if they feel like it.
Below is a quick clip of a cougar attacking an elk.
Oh and one last obvious tip, if you find a cougar kitten in the wild, don't pick it up and play with it. As with moose and bear, encounters with young and a nearby mother are not good at all.
Have fun out there!