Trim is the act of removing irrelevant plant matter from harvested cannabis flowers. This is a post-harvest activity which is also called manicuring.
Trimming plants is essential because it eliminates buds and branches and stems, sugar, and fan leaves. These are difficult to smoke and do not contain significant trichomes, although they do have a few.
Trimming may be done either by wet or dry. Each has its pros and cons, which experienced growers are well aware of.