01In plain English
Fine-tuning takes a model that already works and trains it a little more on a set of examples you provide, such as your brand's writing or your product photos. The result is a version that behaves more like your examples.
02Why it matters when you are choosing
It can give more consistent output than instructions alone, but it takes good examples, time and money. For many jobs, a clear prompt or a tool that reads your documents does the same for less.
03What to check
Ask the vendor
Check who owns the tuned model, where your training data goes, and whether retraining costs extra.