Making sure to enter your data in a standard format will help you better organize, count, and understand it.
Rules can also determine which options you have for working with your data.
You shouldn't change field data type unless you are certain your field data is in the correct format for the new data type.
Changing a field containing only text to the Number type, for instance, will delete all of your field data. Setting the character limit for a field sets a rule about how many characters—letters, numbers, punctuation, and even spaces—can be entered into that field.
If you set the character limit in the State field to 2, users can only enter two characters of information.