11. A non-transitory computer-readable storage medium storing instructions that, when executed by a computing system, cause the computing system to perform operations for text input, the operations comprising: receiving a sequence of input characters corresponding to a user actuating multiple keys represented on an input; computing a character probability for a candidate word of multiple words in a dictionary, wherein the character probability for the candidate word is computed by combining character difference probabilities, and wherein each character difference probability is computed, for each selected character of multiple characters in the sequence of input characters, by applying a probability distribution that indicates, for the selected character, that a character in the candidate word was intended when the key corresponding to the selected character was actuated; and in response to receiving the sequence of input characters, selecting the candidate word, using a processor, based on the character probability for the candidate word.
11. A non-transitory computer-readable storage medium storing instructions that, when executed by a computing system, cause the computing system to perform operations for text input, the operations comprising: receiving a sequence of input characters corresponding to a user actuating multiple keys represented on an input; computing a character probability for a candidate word of multiple words in a dictionary, wherein the character probability for the candidate word is computed by combining character difference probabilities, and wherein each character difference probability is computed, for each selected character of multiple characters in the sequence of input characters, by applying a probability distribution that indicates, for the selected character, that a character in the candidate word was intended when the key corresponding to the selected character was actuated; and in response to receiving the sequence of input characters, selecting the candidate word, using a processor, based on the character probability for the candidate word. 15. The computer-readable storage medium of claim 11 , wherein values in the probability distribution are customized based on one or more of: a category assigned to the user; an analysis of input previously provided by the user; or any combination thereof.