Hmm, interesting. Well like I said, it used to be all Fridays throughout the year, but now it's just during Lent. Except for those 65 or over or something like that.
That's right; the Catholic Church relaxed a lot of regulations during Vatican II, such as the language in which you could say the Mass. In the old days, it was Latin; now Mass may be said in the language of the people, although you occasionally hear about some conservative types who want to bring back the Latin Mass.
And yes, before Vatican II, it was no meat of any kind on any Friday; now it is just on Fridays during Lent. So we Catholics can have sausage or pepperoni on our pizza on Fridays during the rest of the liturgical year. And like I said, it gets a little interesting in my house during Lent because my father (who was originally Presbyterian) will not eat fish. A shame, really, 'cause the rest of us love it.
And the rules are a lot stricter on Ash Wednesday and Good Friday, for in addition to not eating meat on those days, we must fast - which means restricting ourselves to only one large meal and two very small meals (and no snacking) that day. But as Beth said, the very young, the elderly and the health-compromised are exempt from the dietary restrictions.
But I occasionally run into trouble in the dining hall at school on Lenten Fridays, because, let's face it, the dining hall's seafood/vegetarian options often aren't as plentiful or as tasty as the dishes with meat.