An XML parsing system includes a pattern-matching system 1 that receives an input stream 2 of characters corresponding to the XML document to be parsed, and provides an output 3 for subsequent processing in software by a processor 4. The pattern matching system 1 includes two main components, a controller in the form of a programmable state machine 5, which is programmed with an appropriate state transition diagram 6, and a character processing unit 7 in the form of a token and character handler. The programmable state machine 5 controls the character processing unit 7 to, e.g., compare characters in the input character stream 2 with other received or stored characters. The character processing unit 7 then provides feedback to the programmable state machine controller 5, e.g., as to whether the compared characters match, so that the programmable state machine controller 5 can then parse the received document accordingly.