18. The non-transitory computer-readable medium of claim 17 , where the frequency of occurrence of each of the candidate words includes a frequency of occurrence of the candidate word in documents of the user, and where the rank of each of the candidate words is calculated further based on the frequency of occurrence of the candidate word in the documents of the user.
17. The non-transitory computer-readable medium of claim 14 , where one or more instructions, of the plurality of instructions, to calculate the distance factor for each of the plurality of prefixes further include: one or more instructions to determine the distance between the location and the key corresponding to a respective character of the characters as a distance between the location and a center of the key, of the virtual keyboard, corresponding to the respective character of the characters.