Beta reading
Test readers reviewing a manuscript before submission or publication, to harvest real-reader reactions.
Beta reading submits the manuscript to test readers — beta readers — before submission or publication. Their role isn't to correct (that's the proofreader's trade) but to react as readers: where they got bored, where they stopped believing, what they didn't understand, which character they wanted to slap. That's reception data, unobtainable any other way.
Good practice: readers of the target genre (an SF reader will misjudge a romance), a precise brief (three questions beat "tell me what you think"), and an interpretation rule that became workshop proverb: when beta readers flag the same spot, the problem is real; when they propose the same fix, it's usually wrong.
Example
Brief: "Note where you tuned out, the least credible character, and the ending you expected."