Day Parts are hourly time ranges the business can define and name to use for receipt tagging and segment creation.
For example, if your business consistently refers to "Happy hour" as the time between 5:00 PM and 7:00 PM, the business can create a Day Part to use this time range whenever necessary instead of manually entering the hours each time. An additional benefit of this is that, if your company decided to redefine Happy hour as between 5:00 PM and 8:00 PM, you can update your Day Part and every connected segment and receipt tag will update with those new times as well.