我想知 Synchronization其實係咩黎 ???

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Synchronization (or Sync) is a problem in timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time. Systems operating with all their parts in synchrony are said to be synchronous or in sync. Some systems may be only approximately synchronized, or plesiochronous. For some applications relative offsets between events need to be determined, for others only the order of the event is important.

Some uses of synchronization

Whilst well-designed time synchronization is an important tool for creating reliable systems, excessive use of synchronization where it is not necessary can make systems less fault-tolerant, and hence less reliable.

* Film synchronization of image and sound in sound film.
* Synchronization is important in fields such as digital telephony, video and digital audio where streams of sampled data are manipulated.
* Arbiters are needed in digital electronic systems such as microprocessors to deal with asynchronous inputs. There are also electronic digital circuits called synchronizers that attempt to perform arbitration in one clock cycle. Synchronizers, unlike arbiters, are prone to failure. (See metastability in electronics).
* Encryption systems usually require some synchronization mechanism to ensure that the receiving cipher is decoding the right bits at the right time.
* Automotive transmissions contain synchronizers which allow the toothed rotating parts (gears and splined shaft) to be brought to the same rotational velocity before engaging the teeth.
* Synchronization is also important in industrial automation applications.
* Time codes are often used as a means of synchronization in film, video, and audio applications.
* Flash photography, see Flash synchronization
* File synchronization is used to maintain the same version of files on multiple computing devices. For example, an address book on a telephone might need to by synchronized with an address book on a computer.
* Software applications must occasionally incorporate application-specific data synchronization in order to mirror changes over time among multiple data sources at a level more granular than File synchronization. An example use of this is the Data Synchronization specification of the Open Mobile Alliance, which continues the work previously done by the SyncML initiative. SyncML was initially proposed to synchronize changes in personal address book and calendar information from computers to mobile phones, but has subsequently been used in applications that synchronize other types of data changes among multiple sources, such as project status changes.
* The term synchronization is also sometimes used for the transfer of content from a computer to an MP3 player connected to it.