If you just begin your watch collecting hobby, you might be wondering what is the difference between an "automatic" and a "manual" mechanical watch.
To put it simply, an "automatic" wristwatch is a mechanical wristwatch with a self-winding mechanism, that is, one does not have to wind the crown periodically to keep the watch running.
On the other hand, a "manual" or "manual-wind" watch must be wound by hand, using the crown, usually every day, to operate continuously. Whether an automatic or a manual watch is worn depends on individual preferences.
If one was to own only a single watch, and wear it every day, an automatic would be a good choice, since the watch will be worn consistently enough to stay wound - the owner would never need to manually wind the watch, and would only need to adjust the time to compensate for drift and at changeover to daylight/summer time and back.
Reasonably, watches with more than a simple date window use automatic movements - this includes "triple date" calendars, annual calendars, perpetual calendars, and any of these combined with moonphases.
With few exceptions, most manual wind watches have simpler calendars, although they may include other complications like chronographs. If you have more than one watch that is worn regularly, the automatic winding advantage is lessened - the automatic may stop if not worn often.
There can be an increased inconvenience when the watch with some calendar mechanisms, is reset. Additionally, one tends to overlook that a manual-wind watch that is wound consistently once daily can be adjusted such that the day-to-day variation is small, as opposed to the impression that frequently-worn automatics are better adjusted for a more accurate and consistent over the course of many days, since they are usually in the full-wound state.
In short, there is no definite performance advantage to an automatic - it is mostly a convenience.