About choosing a field type
When you define a field, you select a field type based on the kind of information the field will contain. The field type determines what kind of data can be entered and what kinds of operations FileMaker Pro can perform with the data.
FileMaker Pro uses the field type to interpret the data for tasks like sorting records and performing calculations. For example, if you create a text field and enter numbers, you can sort the data only in alphabetical order. (The first character sorts, then the second, so that 11 sorts before 2.) You must use a number field, or a calculation or summary field with a numeric result, to sort data in numerical order.
Important  Be sure to use a date field (instead of a text or number field) to store dates. To avoid confusion when using dates in FileMaker Pro, always use four-digit years. See Defining field validation and Conversion of dates with two-digit years.
You select the field type in the Fields tab of the Manage Database dialog box. To select the field type in Table View, right-click the column heading, choose Field > Field Type > and select one of the options for Field Type.
Related topics 
About defining database fields
Changing field types
Formatting and setting up field objects in Layout mode
Topics in this section
About text fields
About number fields
About date fields
About time fields
About timestamp fields
About container fields
Defining calculation fields
Defining summary fields