A text box allows entry.  This is the most common field type.  There is two types of text boxes, Singleline and Multiline

Singleline
Good for entry such as a First or Last name

Multiline
Good for a comment or description box.

This is a comment box

A text box can be required, have a defined field length and have field validation.  The Insurance Website Builder product uses Regular Expressions to validate entries.