social media

"Social media" is a new term that has become popular in the last five years or so. It means web sites where users share information with each other, like Twitter, Facebook, MySpace, FourSquare, and so on.

lose touch with (someone)

To "lose touch with" someone means to stop communicating with them. It's kind of the opposite of "keeping in touch with" someone.

When you "lose touch with" a person, you stop calling or e-mailing them, and you usually don't know what they've been doing recently.

To explain how long it's been since you contacted a person, use "for":

We lost touch with each other for a few years, but he called me last spring out of the blue and invited me out to lunch.

back (in a time period)

Use "back" to talk about a time period in the past:

Back in the '80s, there was graffiti all over the place in the city.

Back when I was in school, teachers would spank you with a paddlie if you misbehaved.

The time period is usually more than a year ago. It would be strange to use this to talk about something that happened yesterday or last week.

Adding this word makes the time period seem like it was a long time ago.

(get/become/be) big

When something is popular, you can say that it is "big":

Yoga is really big in the U.S. these days.

You can talk about something that's becoming more popular like this:

That kind of restauraunt has gotten big in the last few years.

Or like this:

How did it become so big, so fast?