What is sharing a role / job share?

It's like a micro team - two people share the role and pay of a full-time job. They alternate working days or weeks, have a proper handover, share tools and communications channels, and keep productivity going full time.

What is roleshare.com?
What are the benefits of sharing a role / job share?
How long has this flexible work option existed?
Why have I not heard of rolesharing / job sharing before?
Why roleshare vs. telecommuting vs. part-time
I don't feel like my company really see the value of flexible work?
What's a half job share?
What's a micro team?