When a participant enters their contact details in a Contact Form and completes the submission, a new contact is created and added to the Contacts Manager. You can gain more insights about your contacts by clicking on them in the Manager and opening the Contact Details Card:
This card includes the contact's Personal Data on the left side panel, their interactions with your projects in the middle (Timeline), and the associated Tags and Metrics on the right side panel.
If the same contact completed more than one of your projects, or completed the same project multiple times, you'll see these instances on the Timeline.
You'll also have the option to Delete the contact or change their Opt-In Status. Simply open the dropdown menu in the top left corner of the card (arrow next to email address) to reveal these options.
Pro tip: if you want to access a participant's Contact Card from the Analytics Page's Responses tab, click on the "manage tags" link in the Personal Data section. This will open the Contacts Manager with the participant listed, where you'll be able to click on their email address to open the Contact Card.