According to one estimation, English has 1,100 ways to spell the 44 separate sounds that comprise the language. This is one of the main factors contributing to the difficulty of learning to spell in English. Once a person has identified a sound in a word, she then needs to determine which spelling of that sound applies to the word. One example is the spelling for a long u sound. All the following words contain this sound, but are spelled differently: "shoe," "grew," "glue," "do," "two" and "doom."
Words that sound the same but mean different things or are spelled differently are called homophones and are another reason English spelling is so difficult to learn. Phonetically speaking, similar sounds should be spelled the same way, but this is not the case with homophones. An example is "here" and "hear." If we pronounced words phonetically, these two words would have different pronunciations. It is also difficult for a non-English speaking person to spell homophones because they may not have a clear understanding of the different meanings.
A common mistake spellers make is omitting silent letters or placing them incorrectly. These silent letters are not pronounced but are necessary for a word to be properly spelled. If someone tries to spell phonetically, these silent letters get left out because they are not sounded out. Common examples of silent letters include "knife," "knee," "psychology" and "thought."
Another common barrier to learning English spelling is the doubling of consonants in some, but not all, words. The rule here is to double a consonant after a short, stressed vowel in a longer word; however, consonant doubling often appears after unstressed vowels and some consonants do not get doubled even after a short, stressed vowel. The word "common," for example, contains a short, stressed "o" as do the words "comic" and "dominant," but the latter two words do not have double consonants.
There are 90 basic English spelling patterns that are taught when a person learns spelling; 84 of the patterns have exceptions. In addition, many words deviate from the common English spellings, making English by far the most difficult language to master.