【BitTorrent术语一览】
以下是以BitTorrent协定在对等网络分享档案用的术语。
== 术语 ==
=== 副本数（Availability／distributed copy） ===
用者直接可用的一份档案（或一组档案和目录）的完整副本数。每粒种子都将1加到此数位，因为它们有一份完整的档案副本。如果没有其他对等点拥有档案的这一部分，则有一小部分档案可用的已连接对等点会将该部分添加到副本数中。 示例：下载了65.3%档案的对等节点将副本数提高了0.653。然而，如果两节点都下载了相同的档案部分——比如50%——并且只有一个播种器，则副本数为1.5。  有时认为“分散式副本”是“可用性减1”。因此，如果副本数为1.6，则分散式副本将为0.6，因为它只计算档案的“副本”。
(Also known as distributed copies.) The number of full copies of a file (or set of files and directories) directly available to the client. Each seed adds 1.0 to this number, as they have one complete copy of the file. A connected peer with a fraction of the file available adds that fraction to the availability, if no other peer has this part of the file.
Example: a peer with 65.3% of the file downloaded increases the availability by 0.653. However, if two peers both have the same portion of the file downloaded - say 50% - and there is only one seeder, the availability is 1.5.
Sometimes "distributed copies" is considered to be "availability minus 1". So if the availability is 1.6, the distributed copies will be 0.6 because it is only counting the "copies" of the file.
=== （Choked） ===
描述客户端拒绝向其发送档案片段的对等点。一个客户在几种情况下扼杀了另一客户：
* 第二用户端是种子，在这种情况下它不需要任何碎片（即它完全不感兴趣）
* 用户端已经满负荷上传（已经达到max_uploads的值）
* 第二用户端因滥用行为或正在使用列入黑名单的 BitTorrent 用户端而被列入黑名单。
Describes a peer to which the client refuses to send file pieces. A client chokes another client in several situations:
* The second client is a seed, in which case it does not want any pieces (i.e., it is completely uninterested)
* The client is already uploading at its full capacity (it has reached the value of max_uploads)
* The second client has been blacklisted for being abusive or is using a blacklisted BitTorrent client.
=== 用者（Client） ===
以BitTorrent协定点对点分享档案的程式。请参阅BitTorrent用者端比较。
=== 分散式杂凑表（Distributed Hash Table，DHT） ===
分散式杂凑表在Bittorrent中用于对等点，以将特定种子的群中其他种子／对等点的列表直接发送给用户端，而无需跟踪器。
Distributed Hash Tables (DHT) are used in Bittorrent for peers to send a list of other seeds/peers in the swarm for a particular torrent directly to a client without the need for a tracker.
=== 下载器（Downloader） ===
下载器是没有完整档案但正在下载档案的任何对等点。这个术语在Bram Cohen的Python实现中使用，没有leech的负面含义。Bram更喜欢下载器而不是水蛭，因为BitTorrent的针锋相对确保下载器也上传，因此不会不公平地成为水蛭。
A downloader is any peer that does not have the entire file and is downloading the file. This term, used in Bram Cohen's Python implementation, lacks the negative connotation attributed to leech. Bram prefers downloader to leech because BitTorrent's tit-for-tat ensures downloaders also upload and thus do not unfairly qualify as leeches.
=== 终局／终局模式（Endgame／Endgame mode） ===
用于下载torrent最后几段（见下文）的任何演算法。 在典型的用户端操作中，最后的下载片段比其他下载片段到达得更慢。这是因为应该已经拿到了更快更容易拿到的碎片。为了防止最后的片段变得不可得，BitTorrent用户端试图从它的所有对等点获取最后丢失的片段。在接收到最后一块时，发送取消请求命令到其他对等点。
Any applied algorithm for downloading the last few pieces (see below) of a torrent.
In typical client operation the last download pieces arrive more slowly than the others. This is because the faster and more easily accessible pieces should have already been obtained. In order to prevent the last pieces becoming unobtainable, BitTorrent clients attempt to get the last missing pieces from all of its peers. Upon receiving the last pieces a cancel request command is sent to other peers.
=== 假种子（Fake） ===
假种子是「图文不符」的种子（如称种子是影片，但其实只有影片截图，甚至有恶意软件）。
=== （Freeleech） ===
Freeleech means that the download size of the torrent does not count towards your overall ratio, only the uploaded amount on the torrent counts toward your ratio.
=== （Grab） ===
A torrent is grabbed when its metadata files have been downloaded.
=== （Hash） ===
The hash is a digital fingerprint in the form of a string of alphanumeric characters (typically hexadecimal) in the .torrent file that the client uses to verify the data that is being transferred. "Hash" is the shorter form of the word "hashsum".
Torrent files contain information like the file list, sizes, pieces, etc. Every piece received is first checked against the hash. If it fails verification, the data is discarded and requested again.
Hash checks greatly reduce the chance that invalid data is incorrectly identified as valid by the BitTorrent client, but it is still possible for invalid data to have the same hash value as the valid data and be treated as such. This is known as a hash collision. Torrent and p2p files typically use 160 bit hashes that are reasonably free from hash collision problems, so the probability of bad data being received and passed on is extraordinarily small.
=== （Health） ===
Health is shown in a bar or in % usually next to the torrent's name and size, on the site where the .torrent file is hosted. It shows if all pieces of the torrent are available to download (i.e. 50% means that only half of the torrent is available). Health does not indicate whether the torrent is free of viruses.
=== （Hit-and-run） ===
To intentionally "leech" a file; downloading a file while seeding as little as possible. It's abbreviated HnR or H&R.
=== （Index） ===
Main article: BitTorrent index
An index is a list of .torrent files (usually including descriptions and other information) managed by a website and available for searches. An index website can also be a tracker.
=== （Interested） ===
Describes a downloader who wishes to obtain pieces of a file the client has. For example, the uploading client would flag a downloading client as 'interested' if that client did not possess a piece that it did, and wished to obtain it.
=== （Leech） ===
Main article: Leech (computing)
Leech has two meanings. Often, leecher is synonymous with downloader (see above): simply describing a peer or any client that does not have 100% of the data.
The term leech also refers to a peer (or peers) that has a negative effect on the swarm by having a very poor share ratio, downloading much more than they upload. Leeches may be on asymmetric Internet connections or do not leave their BitTorrent client open to seed the file after their download has completed. However, some leechers intentionally avoid uploading by using modified clients or excessively limiting their upload speed.
=== （Lurker） ===
Main article: Lurker
A lurker is a user that only downloads files from the group but does not add new content. It does not necessarily mean that the lurker will not seed. Not to be confused with a leecher.
=== 磁连结／磁力连结（Magnet link） ===
机制与.torrent档不同，可用于根据内容识别BitTorrent的一组档案，而不是引用任何特定跟踪器，不限于BitTorrent资料。请参阅Magnet URI方案。
A mechanism different from a .torrent metafile which can be used to identify a set of files for BitTorrent based on content, as opposed to referencing any particular tracker. The method is not limited to BitTorrent data. See Magnet URI scheme.
=== （Overseeded） ===
In private trackers using ratio credit, a torrent is overseeded when its availability is so high that seeders have difficulty finding downloaders.
=== 点对点（p2p） ===
Main article: Peer-to-peer
In a p2p network, each node (or computer on the network) acts as both a client and a server. In other words, each computer is capable of both responding to requests for data and requesting data itself.
=== （Peer） ===
A peer is one instance of a BitTorrent client running on a computer on the Internet to which other clients connect and transfer data. Depending on context, "peer" can refer either to any client in the swarm or more specifically to a downloader, a client that has only parts of the file.
=== （Piece） ===
This refers to the torrented files being divided up into equal specific sized pieces (e.g., 64kB, 128kB, 512kB, 1MB, 2MB, 4MB or 8MB). The pieces are distributed in a random fashion among peers in order to optimize trading efficiency.
=== （Ratio credit） ===
A ratio credit, also known as upload credit or ratio economy, is a currency system used on a number of private trackers to provide an incentive for higher upload/download ratios among member file-sharers. In such a system, those users with greater amounts of bandwidth, hard drive space (particularly seedboxes) or idle computer uptime are at a greater advantage to accumulate ratio credits versus those lacking in any one or more of the same resources.
=== （Scraping） ===
Main article: Tracker scrape
This is when a client sends a request to the tracking server for information about the statistics of the torrent, such as with whom to share the file and how well those other users are sharing.
=== （Seed／seeding） ===
A seed refers to a machine possessing all of the data (100% completion). A peer or downloader becomes a seed when it completely downloads all the data and continues/starts uploading data for other peers to download from. This includes any peer possessing 100% of the data or a web seed. When a downloader starts uploading content, the peer becomes a seed.citation needed
Seeding refers to leaving a peer's BitTorrent client open and available for additional individuals to download from. Normally, a peer should seed more data than download. However, whether to seed or not, or how much to seed, depends on the availability of downloaders and the choice of the peer at the seeding end.citation needed
=== （Share ratio） ===
A user's share ratio for any individual torrent is a number determined by dividing the amount of data that user has uploaded by the amount of data they have downloaded. Final share ratios over 1.0 carry a positive connotation in the BitTorrent community, because they indicate that the user has sent more data to other users than they received. Likewise, share ratios under 1 have negative connotation.
=== （Snatch） ===
A torrent is snatched when its data files have been downloaded.
=== （Snubbing） ===
An uploading client is displayed as snubbed if the downloading client has not received any data from it in over 60 seconds.
=== （Superseeding） ===
When a file is new, much time can be wasted because the seeding client might send the same file piece to many different peers, while other pieces have not yet been downloaded at all. Some clients, like Vuze, μTorrent, and qBittorrent have a "superseed" mode, where they try to only send out pieces that have never been sent out before, theoretically making the initial propagation of the file much faster. However the superseeding becomes less effective and may even reduce performance compared to the normal "rarest first" model in cases where some peers have poor or limited connectivity. This mode is generally used only for a new torrent, or one which must be reseeded because no other seeds are available.
=== （Swarm） ===
Together, all peers (including seeds) sharing a torrent are called a swarm. For example, six ordinary peers and two seeds make a swarm of eight. This is a holdover from the predecessor to BitTorrent, a program called Swarmcast, originally from OpenCola.
BitTorrent may sometimes display a swarm number that has no relation to the number of seeds and peers you are connected to or who are available. E.g. it may show 5 out of 10 connected peers, 20 out of 100 connected seeds, and a swarm of 3.
=== （Torrent） ===
A torrent can mean either a .torrent metadata file or all files described by it, depending on context. The torrent file contains metadata about all the files it makes downloadable, including their names and sizes and checksums of all pieces in the torrent. It also contains the address of a tracker that coordinates communication between the peers in the swarm.
=== （Tracker） ===
Main article: BitTorrent tracker
A tracker is a server that keeps track of which seeds and peers are in the swarm. Clients report information to the tracker periodically and in exchange, receive information about other clients to which they can connect. The tracker is not directly involved in the data transfer and does not have a copy of the file. It only receives information from the client.
== References ==