Contact details are located on your contact's profiles, they are the basic info of your contacts.
There are 3 types of properties:
Contact fields: pre-defined fields that you can add for every contact such as emails, phones, job title, companies, URLs, note, birthday, gender, prefix, suffix, middle name, hobbies, addresses.
Smart fields: pre-defined fields auto-calculated by Folk such as last interaction date and number of interactions.
Custom fields: fields you can create on your contacts, they are only accessible by member who have access to the group.
Contact details are fully customizable, you decide which fields to display and in which order. What you choose to display will apply to all contacts from a specific group.