What exactly is the Dragonborn template?

I’m completely unfamiliar with the Dragonborn template, as I’ve never read the sourcebook it has come from, could someone enlighten me as to what it means to be a dragonborn character? Can you summarize?

In what way can it be applied to a character to enhance their roleplaying? Can you choose the type of dragon, or is it randomized? Does it change your physical appearance? Are there any bonuses that would make the character seem special by comparison to the spell slinging rage-wizard?

What are the benefits to being a dragonborn? I already know about the +2 con, -2 Dex and I’m thinking of using it with an elf to eliminate their con penalty. While I know it is sub-optimal to make an elf, the character I’m making is actually an Elf cleric ( Elf domain, Celerity domain ) of Ehlonna. ( She’s a cohort. )

Part of my reason for asking this is that I’m at work and a lot of stuff I have access to is actually firewalled, but the other half is that I’m really interested in hearing others thoughts concerning Dragonborn.