A microcache is a cache whose container is the size of a 35mm film canister or smaller. Most are too small to hold a pen or pencil, and many are too small to hold anything but a log sheet. If there are trade items in such caches, they tend to be very small items, such as coins.
Ideally, microcaches should be hidden in locations where larger containers could not be hidden easily, such as urban parks and plazas. Microcaches in urban settings are often designed and camouflaged for a specific location. Such caches are often called urban micros.
One of the elements that microcaches bring to geocaching is the extra challenge of locating it, as often the vicinity of the cache does not indicate the location of the cache. In many cases, the element of stealth is required as the cache may be hidden in a highly-trafficked spot, which adds to the challenge of locating the cache while non-cachers are present.