Sigma 17-70mm lens came with hood. How and why do I use it?

flare happens with sun and bright lights indoor as well.
I just got a bunch of center pinch lens caps as well for all my Canon and Simga lenses, so they hood is on at all times and I can put the cap on and off without removing the hood now. I ordered from these guys and they are cheap. The cap design is like Tamrons, but cheaper built, but they are also less expensive as well. I personally like Tokina center pinch caps the best, but at bhphotovideo, they are a bit expensive, especially when you have to get like 4 caps.
http://www.fotodiox.co​m/shop/index.php?cPath​=1_16

Lightstream wrote in post #2144370
I was going to say something similar.....or put it on my coffee mug and say "Hey, this is how I put the hood on my glass"

Nah, coffee mugs are made of porcelin, so you would have a hood on your porcelin. Ha ha ha

Tee Why wrote in post #2146245
Nah, coffee mugs are made of porcelin, so you would have a hood on your porcelin. Ha ha ha

*wanders off to find beer glass instead*

In this November's issue of Outdoor Photographer, there is a pretty good article explaining lens flare. It can come from some pretty unexpected sources.

Using a lens hood is a primary way to avoid it and as others have said at the same time protects the lens.

Now that I got a bag today I can carry accessories and don't have to worry about keeping the hood attached or reversed. Once I get where I am going and take the camera out I will just put on the hood and shoot.

One thing I would say about the hood for me, is that went at 17mm and I use the flash I get the dark shape of the petal appear in the bottom of the picture. So Obviously it needs to be removed for that type of shot. Teaching my granny to sucks eggs I know though!