OC

Redditors use OC to mean "original content." You'll most often see this acronym at the start or end of a post's title, to denote the post contains an image, chart, or write-up the OP created.

Why is OC used on Reddit?

Many Reddit posts (especially those made in popular subreddits) contain rehashed or recycled content, which other users may have seen before. The OC tag denotes that a post contains truly original content, which other users won't have seen elsewhere.

Fan fiction writers, artists, and readers use the acronym OC to refer to original, fan-created characters. These characters often star in fan-created stories that also feature official, in-canon characters. For example, a Star Wars fan whose headcanon includes a cool bounty hunter that once dated Obi-Wan Kenobi may end up writing a fan fic starring their OC and Obi-Wan.

What's the difference between OCs and fan characters?

In some creative circles (such as on DeviantArt), OC refers to truly original characters who are not tied to any existing intellectual property. In those circles, the term fan character is used to refer to fan-created characters who are tied to an existing story, game, or other work.

A simple reply to an obvious statement; may also be used within a sentence.