Refers to the culinary definition of fruit: a sweet and/or seed-containing part of a plant that roughly resembles a botanical fruit, even if it is not a seed-containing botanical fruit.
Use the fruit tag for questions about any kind of fruit, especially questions that are generally about fruit and not necessarily a specific fruit.
If the subject is a specific fruit then consider including the specific tag as well (e.g. apples).
Note that culinary fruits are a fuzzily-defined category; please simply use the tag if you feel it makes sense for the food in question.