How much does 1GB of data get you?

How much can you do with 1 gb of data. There is a plan on AT&T where it's just $85 a month for an iPhone with 1 gb of data. I was wondering how much I would need. I would go on websites like Instagram and NOT Youtube because it eats up data with videos. So I was just wondering and also is it possible to go over your data limit so it will charge you extra.

Added (1). Wow sry I totally made that unclear you get 450 minutes of phone service, unlimited texting, and 1 gb of data all for $85. Not just 1 gb of data for $85. I never use the phone so I chose the lowest minutes and then unlimited texting. But I was wondering if 1gb of data is good enough or if I would need more.

Not a lot

I use a iPhone 5 on T-Mobile and I pay $50 a month for unlimited data, messaging, and texts! I love having everything unlimited and T-Mobile has LTE which is equal to att

Wow that's a high price for very little data. Check out mine, it's unlimited for $49.00 at 4G. They do throttle you but after like 4gigs. Unlimited talk, text, data it's a set price so you never worry about getting charged extra. They use the same Towers they just give you more. T-mobile slows you down after you use 100 megs so make sure you check that fine print.
www.solavei.com/joegenius

Oh I forgot to mention if you sign up 3 people you get $20 every month.