Unions - what is their purpose?

What do they do for us? Cause trouble or help out?

What I had as benefits as a federal government employee were due to the unions. My dental insurance certainly was useful to me recently.

A friend is hoping to go back to work after a long absence. She said that there was a big meeting with the union to help get her pointed in that direction.

I was reading about OC Transpo and the union - they are meeting regularly. Relations between them after the big strike last year are still not easy. The contract comes up next year. They voted some time ago that they can still go on strike. Oh dear!!