Cyrillic characters in browser address bar

When I put cyrillic symbols in address bar like this:

http://ru2.php.net/manual-lookup.php?pattern=привет

it switches to

http://ru2.php.net/manual-lookup.php?pattern=%EF%F0%E8%E2%E5%F2

What does that characters -- %EF%F0%E8%E2%E5%F2 -- mean? And why is it happening?

The characters are getting URL encoded. A URL may only contain a subset of ASCII characters, so anything outside plain alphanumeric and some special characters must be URL encoded.

Some browsers display non-ASCII characters as human readable characters, but that's entirely up to them. In protocols, URLs are always URL encoded.