What is AI training / data annotation work, exactly?

Keep seeing ads for jobs that pay you to 'train AI.' What does that actually involve day to day?

AI training and data annotation work covers a range of tasks that help improve machine learning models by having a human do something the model can't yet do reliably on its own. Depending on the platform and project, that might mean labeling or tagging images, transcribing or classifying audio and text, comparing two AI-generated responses and picking the better one, writing example question-and-answer pairs, reviewing AI-written code for correctness, or rating outputs against a detailed guideline document. It's essentially structured piecework: you get a task, a rubric or instructions, and you complete it within that framework — there's rarely any need to build or understand the AI model itself. The reason this work exists at all is that current AI models still can't reliably judge their own output quality at the level labs need, so human judgment gets used to create the data that trains and evaluates them.