@ symbol in php and chown questions

I was looking up some info on the copy function in php, on their website and some of the comments use the copy function as such,

@copy($source, $dest);

what does the @ do?

another thing, is after i copy my files, they are all owned by httpd. how do i change these back to my ftp username. I tried using right after the copy function chown, but to no avail. also, al the files are 644. how would i go about chmoding them to 755?

thanks