What’s a leech in CompSci?

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A leech is someone who takes data, resources, or bandwidth without giving something of equal value. This can happen in various ways, such as stealing Wi-Fi or linking to an object on another site. In the world of torrents and binary USENET newsgroups, being a leech has different meanings.

A leech is a person who sucks up data, resources, or bandwidth from a network or website in a manner considered ethically questionable or exhibits poor netiquette. This usually means burdening the target without returning something of equal value. The leech has an additional meaning in the world of torrenting, and again in the binary USENET newsgroups where being a leech is perfectly acceptable. so what are the differences?

In the wireless world, a leech is someone who steals bandwidth by stationing themselves outside a wireless cafe, for example, so they can use the service without frequenting the cafe. A neighbor who uses his neighbor’s network without permission is also considered a leech.

Another type of leech occurs when a website links to an object located on a non-affiliated site. For example, Bob creates a website and links to a picture on Jean’s site. When someone visits Bob’s page, it appears that the image is there, but in reality, Bob’s site requests the image from Jean’s site with every visitor to his page. Bob is stealing bandwidth from Jean, as the server hosting her site uses the allocated bandwidth to serve the image to Bob’s site. Bob is a leech.

In the world of torrents, anyone who downloads a file is referred to as a leech until they receive the entire file and start passing it back to others. In this sense being a leech is a function of the network. However, successful torrent networks are built on fair sharing, so anyone who takes more than they give in a period of time is considered a leech in the negative sense. Torrent software deters leeches by limiting bandwidth to those with low share ratios.

In binary USENET newsgroups where files are posted for download, leeching does not have a negative connotation because the newsgroup protocol is not based on fair sharing. People can download as many files as they want without the responsibility to reciprocate. So, a USENET leech isn’t a bad thing, as evidenced by one of the most popular binary newsreaders, NewsLeecher.
Aside from USENET and the necessary torrent download feature, being a leech is a tag to avoid. Everyone benefits when people practice good netiquette, which is why the concept exists.




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