How much data should I get for an iPhone 5s?

I want to start a plan with AT&T and its asking how much shared data I want and I don't know which one to choose. To be completely honest I don't even know what shared data even means. I googled it and some people say its like the internet usage but i'm not completely sure. I used to have be in a family plan on sprint with my uncle and I didn't even know how much shared data we had.

I'm always connected to my Wi-Fi when I use my phone at home and I'm at home almost all day. When I'm at home, I'm always browsing my feeds on instagram, facebook, twitter, checking my emails, etc. I don't use my phone a lot when I'm out of the house, I only use it to google things. Sometimes I'll go on instagram, etc or i'll check my emails when I'm in the waiting room for an appointment or something. Btw, I'm starting this plan with my two sisters. How much data should we get?

Its good that you have shared a lot of details but now as you are sharing this data with your 2 sisters you would also need their data usage. For you i think 500mb-1gb data would be fine