Search $string and return what's between $start and $end. It's simple, doesn't use regex, so it's just a useful cleaver to pick up when you need to extract some content but it's not in a structured format (but you know it's the bit that comes between, say: '</head>' and '<div id="footer">' OR between 'Amy says' and 'Do not tell a soul'). You can use this to salvage nodes from an XML file that won't parse, or any number of things.