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.
来源：https://stackoverflow.com/questions/6483613/cyrillic-characters-in-browser-address-bar