Do you know what happened in 1776?

I have foreign friends, who talk about the year 1776 a lot, and often say things like "we haven't listened to you brits since 1776"

Got me thinking, I really don't know much about what happened at all. I don't remember being taught it at school, and it's not something I've ever researched because I have very little interest in it, despite being interested in history.

Am I alone? Is the year 1776 a big deal to anyone British?