When creating a custom field you will notice that there are options to what type of field you are creating is. The difference may be confusing at first but once you understand, you will be able to utilise the different types to capture the type of data you want.
Text fields are the simplest of the custom field types. A text field allows the contact input their own information into the field. This type of field is good for information like first name and last name. The field should only be used for information that would be unique to each individual contact apart from dates.
Choices fields are a good form of field for information that you want to be restricted. A good example of this is location. Although Location could be achieved via a text field, a customer may spell it wrong etc. which makes it difficult for you to filter the contacts afterwards. With a choices field you can set the choices and then they can choose upon sign up.
There are three types of choices:
Dropdown allows the contact choose one option from the dropdown box that the field will provide. A Drop down field is better for a field with many options. A Good use for the drop down box is the location example. The contact can choose their location from the long drop down box of all the areas you have provided.
A Radio Field Lets you choose one option from the options presented in front of you. This is best used for a field with few options. A Good example of this would be gender. The contact would only have a few options compared to other fields like location that might have 15 choices etc.
A checkbox field allows the contact to choose more than one option from the list. You may do this for a field like favourite car. They may have more than one favourite car so they have the option to select many choices.
Date fields are fairly self-explanatory. They allow the user to input a date into the field. The date field can be used for fields like available between dates for when you are trying to arrange a meeting etc.