OP

OP is short for "original poster," the user who started a given thread or comment chain. When someone writes "OP, can you share which tool you ended up using?" they are asking the person who created the post, not the broader community.

The term is useful because Reddit threads often grow long and the original question can drift. Pointing back to OP is a way to keep the conversation grounded in what the asker actually wanted. Reddit's interface visually marks the OP's replies with a small badge so readers can find their follow-ups quickly.

For marketers, OP is the most important user in any keyword-monitoring match. If someone posts "anyone using a tool that monitors Reddit for keyword mentions?" the OP is your potential customer. Replying to a side thread or to a commenter is far less valuable than getting OP's attention with a useful, honest reply. Most experienced Reddit responders address OP by name or directly with "Hey OP" to make the relevance obvious.

OP also has implicit authority in their own thread. They can update the post (often labeled EDIT: or UPDATE:), mark the question as resolved, or flair the post as Solved in subs that support it. When you reply with a helpful answer and OP edits the post to credit your suggestion, that endorsement carries significantly more weight than a normal comment because lurkers reading later will see it.

Acronyms like OP are part of the broader Reddit shorthand vocabulary alongside ELI5 (Explain Like I'm 5), TIL (Today I Learned), and TL;DR (Too Long; Didn't Read). Understanding them is a small but real signal that you're a participant in the culture, not a visitor.