The phenomenon of keeping pets has been around for thousands of years. But just think about it for a moment: you take in a creature of a different species, feed it, look after it, love it, and maybe even let it sleep on your bed. The problem is you don't really know what its behaviour means and how to deal with it.
Part of the responsibility of being a pet owner is finding out what the cat means when it slowly blinks its eyes (it's smiling) and why it doesn't work when you shout at the dog to stop barking (it thinks you're joining in on the game with a bark of your own). And this is just scratching the surface. That's why the internet is so great – the info is available. Starting with the link below.
Behavioural problems in pets