<Li> An optional message body . </Li> <P> The status line and other header fields must all end with <CR> <LF>. The empty line must consist of only <CR> <LF> and no other whitespace . This strict requirement for <CR> <LF> is relaxed somewhat within message bodies for consistent use of other system linebreaks such as <CR> or <LF> alone . </P> <P> Below is a sample conversation between an HTTP client and an HTTP server running on www.example.com, port 80 . As mentioned in the previous sections, all the data is sent in a plain - text (ASCII) encoding, using a two - byte CR LF (' \ r \ n') line ending at the end of each line . </P> <P> A client request (consisting in this case of the request line and only one header field) is followed by a blank line, so that the request ends with a double newline, each in the form of a carriage return followed by a line feed . The "Host" field distinguishes between various DNS names sharing a single IP address, allowing name - based virtual hosting . While optional in HTTP / 1.0, it is mandatory in HTTP / 1.1 . </P>

Explain how ftp and http are used on the internet