grabbing source of a URL

Hi, I don't know what functions to use so maybe someone can help me out. I want to grab a URL's source (all the code from a link) and then cut out a block of text from it, throw it away, and then show the page. For example, if I have page.html with 3 lines: <html><head><title>hi</title></head> <body> <!-- line a --> this is line a <!-- end line a --> <!-- line b --> this is line b <!-- end line b --> <!-- line c --> this is line c <!-- end line c --> </body></html> i want my php script to grab the source of page.html, strip out: <!-- line a --> this is line a <!-- end line a --> and then display what is left, how would I go about doing this? I don't know what function to use to grab the page. for the string to remove, I know I can probably do a str_replace and replace the known code with nothing.