Definition of Alphanumeric

Alphanumeric is said of everything that uses both letters and numbers. Alphanumeric in English.

It can also sometimes include other special characters, such as punctuation marks and math symbols. But if we stick to the strict definition, it should only include letters and numbers.

In lower case there are 36 characters, from A to Z and from 0 to 9. If we include capital letters there are 62 alphanumeric characters. In Spanish, accented vowels, the letter and the diresis could also be included, although many computer systems may not consider these alphanumeric characters, so this must always be taken into account.

So when, for example, we are asked to create an «alphanumeric» password or username, it means that we can only choose a word that contains only letters and numbers. It probably doesn’t allow spaces, accented vowels, or special symbols.

Representation of alphanumeric characters in computers

In computers, storing an alphanumeric character takes up less than an 8-bit ASCII character.

All alphanumeric characters can be represented with 6 bits (6 bits allow 64 possible values).

Specifically what are the alphanumeric characters

Basically the alphanumeric characters are:

0 1 2 3 4 5 6 7 8 9

ABCDEFGHIJKLMNOPQRSTU VWXYZ

ABCDEFGHIJKLMNOPQRSTU VWXYZ

In Spanish should include the () and accented vowels: , , , , , as well as the diresis «»
Although in systems programmed in English they may not accept these Spanish letters as alphanumeric, so caution should be exercised in those cases.

Alphanumeric password, username, and address

It is usual that in forms, records or identification in services, etc., we are asked to enter some field in alphanumeric. This text field can be an alphanumeric password, user name, address, etc.

Many users wonder «What did I enter there?», because many times the form is rejected when it is sent.

Basically you have to enter what corresponds (a username, a text, a password…) using only LETTERS and NUMBERS. As said before, be careful with accents, because not all systems accept them as alphanumeric.

It is usual that the form imposes other limitations such as, for example, that the entered word has a maximum or a minimum number of characters.

You must carefully read the specifications of the form to correctly enter the request and thus it is not rejected.

alphanumeric postal code

Many queries come to the Dictionary regarding an alphanumeric code that they must type into certain forms. In many countries they have changed from the classic numerical postal codes to the most modern alphanumeric postal codes, that is, not only numbers are used for the postal code but now letters are included.

To determine the alphanumeric postal code of a specific place, you must enter the official website of the official postal service of the country. There will probably be a section that will allow us, using a postal address, to find out what new alphanumeric postal code corresponds to it.