(zero valuebytes that can cause problems for libraries and networking because their encodingscharacter maps assign characters to the same codes for compatibilityascii is subset of both latin- and utf- that isa valid ascii character string is also valid latin- and utf- -encoded string for exampleevery ascii file is valid utf- filebecause the ascii character set is -bit subset of utf- converselythe utf- encoding is binary compatible with asciibut only for character codes less than latin- and utf- simply allow for additional characterslatin- for characters mapped to values through within byteand utf- for characters that may be represented with multiple bytes other encodings allow for richer character sets in different ways utf- and utf- for exampleformat text with fixed-size and bytes per each character schemerespectivelyeven for characters that could otherwise fit in single byte some encodings may also insert prefixes that identify byte ordering to see this for yourselfrun string' encode methodwhich gives its encoded bytestring format under named scheme-- two-character ascii string is bytes in asciilatin- and utf- but it' much wider in utf- and utf- and includes header bytess 'nis encode('ascii') encode('latin ') encode('utf '( 'ni' 'ni' 'ni' encode('utf ')len( encode('utf ')( '\xff\xfen\ \ ' encode('utf ')len( encode('utf ')( '\xff\xfe\ \ \ \ \ \ \ \ ' these results differ slightly in python (you won' get the leading for byte stringsbut all of these encoding schemes--asciilatin- utf- and many others--are considered to be unicode to python programmersencodings are specified as strings containing the encoding' name python comes with roughly different encodingssee the python library reference for complete list importing the module encodings and running help(encod ingsshows you many encoding names as wellsome are implemented in pythonand some in some encodings have multiple namestoofor examplelatin- iso_ and are all synonyms for the same encodinglatin- we'll revisit encodings later in this when we study techniques for writing unicode strings in script for more on the underlying unicode storysee the python standard manual set it includes "unicode howtoin its "python howtossectionwhich provides additional background that we will skip here in the interest of space string basics