Symptoms are itchy bottom, sometimes blood when doing a poo, sometimes mucus, if external then a little lump will be felt, and there can be excruiating pain when having a poo.
As netibiza says, and Its often caused by, and made worse by constipation. its not usually a big deal, you can get cream over the shelf in the chemist and also worth a visit to the Doctor.
Make sure you eat more fibre (not so much bran but more fruit & veg) and drink lots of water. The wetter/softer the poo (sorry!) the easier to pass and less damage to your soft bits!
Wow... I've had a little tiny lump there for ages, but didn't realise that it could be haemarroids! Will cream sort it back out even though its been there for ages? It doesn't hurt usually, but sometimes, it feels like it (er....) splits a tiny bit, which feels quite sharp.
What people are discussing here also sounds like an anal fissure- blood, sometimes lots, razor sharp pain when pooing, then spasms a few minutes after. I thought I had piles again but turned out it was one of these and anusol wasn't doing nothing.
I agree mormess that anal fissures can cause bleeding - had one myself with an ulcer on it to boot!! The reason I mentioned Anusol HC was in relation to lynneylou's Q...