May be a stupid question, but please help?

I've heard a lot about Doctor Who and I've had a mind to start watching it. I was just wondering how the storyline operates exactly. It's supposed to be a long-running series and everything and I just want to know if I'll be able to understand what's going on if I start watching from series 1 (2005) ie. will there be references, etc. that I might not understand. Wikipedia says the series adheres to original continuity. I'm just really confused.