Contact details are located on your contact's profiles, they are the basic info of your contacts.
There are 3 types of properties:
Person fields: pre-defined fields shared on every contacts such as first name, last name, emails, phones, job title, companies, URLs, note, birthday, gender, addresses.
Smart fields: pre-defined fields shared on every contacts, auto-calculated by folk such as last interaction date, number of interactions and strongest connection.
Custom fields: fields you create in your groups (proper to a group), such as custom tags, dates, text etc...
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. Just click on visible fields, to select the right fields and re-order them the way you want.