utf8_encode
    (PHP 3>= 3.0.6, PHP 4 )
utf8_encode -- encodes an ISO-8859-1 string to UTF-8
Description
string 
utf8_encode ( string data)
     This function encodes the string data to
     UTF-8, and returns the encoded version.
     UTF-8 is a standard mechanism used by
     Unicode for encoding wide
     character values into a byte stream.
     UTF-8 is transparent to plain ASCII
     characters, is self-synchronized (meaning it is possible for a program to
     figure out where in the bytestream characters start) and can be used with
     normal string comparison functions for sorting and such.  PHP encodes
     UTF-8 characters in up to four bytes, like this:
     
Tabulka 1. UTF-8 encoding
| bytes | bits | representation | 
|---|
| 1 | 7 | 0bbbbbbb | 
| 2 | 11 | 110bbbbb 10bbbbbb | 
| 3 | 16 | 1110bbbb 10bbbbbb 10bbbbbb | 
| 4 | 21 | 11110bbb 10bbbbbb 10bbbbbb 10bbbbbb | 
     Each 
b represents a bit that can be
     used to store character data.