php://filter

php://filter is a stream filter that allows developers to apply various filters to input and output streams in PHP. This feature can be used to modify, validate, or sanitize data before it is sent to or received from a client or server.

Some of the filters that can be applied using php://filter include:

- Convert character encoding using the iconv filter
- Compress output using the zlib filter
- Sanitize input using the strip_tags filter
- Validate input using the validate_email filter

The php://filter stream wrapper can be used to apply these filters to various types of streams, including files, network sockets, and HTTP requests and responses. This can help to improve the security and reliability of web applications by ensuring that data is properly validated and sanitized before it is processed.