Working for free

mobility
the ability to move freely or be easily moved

I prefer the mobility of a hand-held camera.

internship
a period of time during which someone works for a company or organization in order to get experience of a particular type of work

Jane has a summer internship at a local TV station.

I think it's good to get a internship when you're a student. But I don't understand the unpaid internships. I can get a part-time job even if  I'm a student.  Why I need to get a unpaid job?  If I finish my unpaid internship and the company doesn't want to keep hiring me. I waste my time in this unpaid internship.