Shared steps
A shared step is a block of steps maintained in one place and used in many test cases. "Sign in as a returning customer" is written once; the forty cases that start with it point at that one definition.
Creating one
Settings → Shared steps → New shared step. Give it a name and the steps it contains, exactly as you would inside a test case.
Using one
In a test case's step editor, insert a shared step instead of writing a new one. It renders in place, in order, marked as shared so a reader can see the block is maintained elsewhere.
What changes when you edit one
Editing a shared step changes every case that uses it, from the next time each is read. That is the point, and it is also the risk: a shared step used by forty cases is a forty-case edit. The screen tells you how many cases reference it before you save.
Executions already recorded are untouched. A bug hunt holds a copy of the case as it was, so a shared step edited today does not rewrite what a tester saw last week.
When not to use one
If two cases share three steps by coincidence rather than by meaning, leave them alone. A shared step is a statement that these steps are the same thing and should change together. Extracting every repeated pair produces a library where no case can be read end to end without opening four other records.
Availability
Shared steps are available on every plan, including Free.