Fixed date automation is where you can create a series of actions, including email and SMS communications, on specific calendar dates and times. To do this, you can start by creating a new campaign and then on the next page is where you select the relevant boxes to make it a ' Fixed date automation'. 

When your fixed date automation is started, you add your contacts in so that they will be sent your communications on those specific dates with those specific times.

For example you have an event on a specific date and time and you want to market that event, send pre-event communications out and also communications on the date itself at prescribed times. You may even want to send a survey the day after your event, which you can add to your date-based automation.

In addition to marketing communications to prospects / customers you can also build in other actions such as create a task, create lead/sale and add/remove from a group.