A filter may refer to any of the following:
1. The most common filter is a software filter or a filter in a program that reads data in and manipulates the data to fit another output pattern or removes data that may not be needed. For example, spam filters help filter unwanted e-mail from reaching your Inbox.
3. Alternatively referred to as censorware, a swear filter, or a content filter, a filter can be used to describe software or hardware which selectively blocks certain data. For example, a parental control Internet filter can be used to help block obscene websites from children on the Internet.