English orthography is the system of writing conventions used to represent spoken English in written form that allows readers to connect spelling to sound to meaning.
Like the orthography of most world languages, English has a broad degree of standardization. However, unlike most languages, there are multiple ways to spell nearly every phoneme (sound), and also most letters have multiple pronunciations depending on their position in a word and the context. Several orthographic mistakes are common even among native speakers. This is mainly due to the large number of words that have been borrowed from a large number of other languages throughout the history of the English language, without successful attempts at complete spelling reforms. Most of the spelling conventions in Modern English were derived from the phonetic spelling of a variety of Middle English, and generally do not reflect the sound changes that have occurred since the late 15th century (such as the Great Vowel Shift).
Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most recognized variations being British and American spelling, and its overall uniformity helps facilitate international communication. On the other hand, it also adds to the discrepancy between the way English is written and spoken in any given location.
Note: In the following discussion, only one or two common pronunciations of American and British English varieties are used in this article for each word cited. Other regional pronunciations may be possible for some words, but indicating all possible regional variants in the article is impractical.