A custom field can be of 6 different types and here's how they look like.
Text field
A text field that allows entering any type of character.
Number field
A number field allows entering any number in the text field.
Single option
The single option field is a drop down list that allows selecting only one option.
Multiple options
The multiple option field is also a drop down list but allows selecting more than one option at a time.
Date field
Allows selecting a date from a calendar.
Multiline text
A text field that allows entering multiple lines of text.
Currency
A number field that formats into a currency.
Link
Allows entering a hyperlink to a file or web page in the Internet.
Address
Allows enter an address that auto completes automatically from a database of addresses.
Contact
Is a drop down list of the contacts in the system.
