<P> UTF - 8 is a variable width character encoding capable of encoding all 1,112,064 valid code points in Unicode using one to four 8 - bit bytes . The encoding is defined by the Unicode standard, and was originally designed by Ken Thompson and Rob Pike . The name is derived from Unicode (or Universal Coded Character Set) Transformation Format--8 - bit . </P> <P> It was designed for backward compatibility with ASCII . Code points with lower numerical values, which tend to occur more frequently, are encoded using fewer bytes . The first 128 characters of Unicode, which correspond one - to - one with ASCII, are encoded using a single octet with the same binary value as ASCII, so that valid ASCII text is valid UTF - 8 - encoded Unicode as well . Since ASCII bytes do not occur when encoding non-ASCII code points into UTF - 8, UTF - 8 is safe to use within most programming and document languages that interpret certain ASCII characters in a special way, such as "/" in filenames, "\" in escape sequences, and "%" in printf . </P>

For characters from english alphabet how many bytes are used per character