When you deploy your script to the Apify Cloud, it becomes an actor. An actor is a serverless microservice that accepts an input and produces an output. It can run for a few seconds, hours or even infinitely. An actor can perform anything from a simple action such as filling out a web form or sending an email, to complex operations such as crawling an entire website and removing duplicates from a large dataset.
To run an actor, you need to have an Apify Account. Actors can be shared in the Apify Library so that other people can use them. But don't worry, if you share your actor in the library and somebody uses it, it runs under their account, not yours.