Use the Textfield input type for a basic text input box.  Note: the maximum length (out of the box) of any submitted value is 255 characters. 

In the Validation section, you can set that to be less than 255 characters, if you always expect a certain format, such as a 5 digit zip code. 

In the Display section, you can also set a prefix or postfix next to the text input box. These values [prefix and postfix] are not saved into the database; they are merely helper text/labels.