Swear filter

A swear filter, also known as a profanity filter or language filter is a software subsystem which modifies text to remove words deemed offensive by the administrator or community of an online forum. Swear filters are common in custom-programmed chat rooms and online video games, primarily MMORPGs. This is not to be confused with content filtering, which is usually built into internet browsing programs by third-party developers to filter or block specific websites or types of websites. Swear filters are usually created or implemented by the developers of the Internet service.

Function

Swear filters typically take advantage of string replacement functions built into the programming language used to create the program, to swap out a list of inappropriate words and phrases with a variety of alternatives. Alternatives can include:

• A sequence of shift-number characters, such as !@#$%^&*
• Replacing a certain letter with a shift-number character, so the U in "fuck" would be replaced by a V to create "fvck", the S and/or I in "shit" would be replaced by a dollar sign ($) or exclamation mark (!) creating "$hit", "sh!t" or "$h!t" and so on.
• Asterisks (*) of either a set length, or the length of the original word being filtered, like if "fuck" were to be filtered, it would appear as "****". Alternatively, posters often replace certain letters with an asterisk, creating "f*ck", "f**k", "f***" and so on.
• Made up words such as "Flum".
• Family friendly words or phrases, like "LOVE" or "I LOVE YOU", or completely different words which have nothing to do with the original word.
• Deletion of the post. In this case, the entire post is blocked and there is usually no way to fix it.
• Nothing at all. So if "fuck" were filtered, "fuck your couch" would become " your couch"

Some swear filters do a simple search for a string. Others have measures that ignore whitespace, and still others go as far as ignoring all non-alphanumeric characters and then filtering the plain text. This means that if the word "you" was set to be filtered, "y o u" or "y.o!u" would also be filtered.

Unintended consequences

Further information: Unintended consequence

Further information: Scunthorpe problem

A common quirk with swear filters, often considered either comical or annoying by users, is that they often affect words that are not intended to be filtered. This is a typical problem when short words are filtered. For example, if the word "ass" is filtered, so may "glass", "molasses", "assassin", and other words which contain the sequence "ass". Or, words such as "Uranus" or "Manuscript" may be filtered in the case of "anus". Multiple words may also be filtered if whitespace is ignored, often resulting in sequences such as "As suspected" becoming "****uspected".

Some words that have been filtered accidentally can become replacements for profane words. One example of this is found on the Myst forum Mystcommunity. There, the word 'manuscript' was accidentally censored for containing the word 'anus', which resulted in 'm****cript'. The word was adopted as a replacement swear and carried over when the forum moved, and many substitutes, such as " 'scripting ", are used (though mostly by the older community members).

Place names may be filtered out unintentionally due to containing portions of swear words. In the early years of the internet, the British place name Penistone was often filtered out from spam and swear filters [1].

Also, sometimes there are unintentionally made ways to get around filters, with words such as "Pen Is" and "Mo Lester" getting through the filter.

Implementation

Many games, such as World of Warcraft, and more recently, Habbo Hotel and RuneScape allow the user to turn the filters off. Other games, especially free Massively multiplayer online games, such as Knight Online do not have such an option. There are also profanity filter web services, such as, http://www.webpurify.com

See also

• Medireview
• Scunthorpe problem