It seems ironic to be defining the term 'dictionary,' but here we go! Dictionaries are resources for finding word meanings, parts of speech, word origins and even synonyms and antonyms. Dictionaries have definitely evolved over the years. The English language really began with the Anglo-Saxons in Great Britain.
If it is a US Passport, that it is the 9 digit number located in the top corner of the passport info page. In the example below the passport number is 31195855. Other Countries have different types of numbers (usually with letters added) but most often it's in the same place. This Canadian Passport number is AB504966.
Visa number: the visa number is the eight digit number in red located in the lower right-hand corner. If the visa was issued prior to 2002, the visa will look slightly different than the picture above but the number is located in the same place. For visas issued before 2000, the number is located at the top of the visa in the center. Like the other two it is also red in color.