The Contact History allows you and anyone you share your addresses with (they don't have to have edit rights to the address) to add separate entries that give details on when you last contacted someone in your Address Book.

Each entry in the Contact History will list what date the comment was made, who made it, the account name of the person that made it, and what the note is about. You also have the option of adding a follow-up task to your Contact History entry to your To Do List in case there's a future action you need to make regarding that contact.

Note: In order to add a follow-up task to a contact you must already 1) have the To Do application turned on and 2) have already created a To Do List. 

To add a follow-up task to your Contact History entries you must first create an entry. Follow the steps in the image below:

Once you've clicked on the green "New Entry" button you'll see your entry has been added to the Contact History for your address. You'll also see a blue "Add follow up task" link to the right. Click on that link and follow the instructions below:

You can choose to add a follow-up task to a To Do List in your account, or to a To Do List that has been shared with you.

When you click on the checkbox next to "Send me a reminder" you'll notice that you won't be able to customize when and how the reminder is sent. The reminder will be sent at the default schedule, which is 5am the same day as the due date and the message is sent by email and text message.