This piece on trekking poles is one of the very first things I ever wrote. The pictures are all from a backpacking trip in Mt Rainier National Park and our group was small, but lots of fun.
The primary reason to carry a trekking pole is because using it reduces the stress on your knees by 25% when you're going downhill. Even women who never have knee problems sometimes start feeling twinges when they go steeply downhill. The bigger the step down, the more you'll appreciate how much a trekking pole helps.
Of course, using a trekking pole when you're stepping up or going up hill is helpful too. Sometimes it gives you that little boost you need, especially at the end of a long day or when your pack is heavy.
But the real revelation is how many other uses there are than simply using them for hiking!
Improves your balance when crossing a stream
Allows you to wet your bandanna without taking your pack off or bending too far over
Great as a hat rack. Or a good place to dry your
clothes after you've washed them
Gives you a third leg for crossing slippery snow fields
Supports your pack when you're taking a break, so everything stays upright. If you do it right, you can then use your pack as a back rest.
Assists you in picking up trash and helping keep the wilderness litter-free
Its also useful for assisting with setting up a tight tarp.
And last, but not least, they're great fun for playing with, especially on chilly mornings when you want to warm up before putting your pack on.