PHP symbols ... reverse lookup

Where might I find a complete list of the PHP symbols? (... in one place?) I can't find anything like that on PHP.net/docs.php. Google didn't help, either! For example, I often find myself reading a PHP book, that doesn't fully define symbols, utilized in its code examples. Say I wanted to look up (i.e. define) what the following mean ... => (e.g. Is this the same or different from >= ? ) :$variableName (e.g. What's the colon signify?) These symbols may be buried in various categories; but, are they listed somewhere all together - for reverse lookup? thanks, Mike