A Latin-derived alphabet is an alphabetical writing system that uses letters of the original Roman Latin alphabet and extensions. Extending can be done by adding diacritics to existing letters, joining multiple letters together to make ligatures, creating completely new forms, or assigning a special function to pairs or triplets of letters. These new forms are often given a place in the alphabet by defining a alphabetical order or collation sequence, which can vary with the particular language. Some extensions, especially letters used with diacritics are not considered separate letters, e.g. French é or German ö are not used in the commonly quoted alphabet sequences. The Basic modern Latin alphabet is the most well known Latin-derived alphabet. The International Phonetic Alphabet is also Latin-derived. The tables below summarize and compare some of the alphabets known to the various contributors.