1. Literally, to wait in a line of people. This shouldn't take much longer—mom's in line to pay right now. People who wanted to get one of the early smartphones would be in line for hours, if not days!

2. To be a likely recipient of something, such as a job or an award. I'm pretty sure I'm in line for Connie's position once she retires. My daughter is a great student, so she's in line for many academic awards at graduation.

3. To conform, adhere to, or agree with that which is established or generally accepted, such as rules, beliefs, modes of behavior, etc. You might have some wild ideas for the future, but you'll never get anywhere in this business if your actions aren't in line with your boss's expectations.

4. To be an area of skill or interest for someone. In this usage, a pronoun is usually used between "in" and "line." My mom studied art in college, so it's not surprising that photography is in her line.