Reddit glossary
What is Pinned (sticky) post on Reddit?
A pinned post, also called a sticky, is a post a moderator keeps at the top of a subreddit.
Mods pin the rules, announcements and weekly threads. It is a good sign of what the community considers important.
If you are promoting something
Read the pinned posts first. They often hold the answer to the exact question you were about to ask the mods.