Apple's reminder app has never been particularly sexy and appealing, but that changes in iOS 13. Although the productivity tool was always useful for quick tasks, it now has a redesigned interface with several new features, including grouping lists in common for a better organization.
Prior to iOS 13, you can only create lists that are stored on your iPhone, in iCloud, or with a third party such as Yahoo or Outlook with reminder access. They were all confused on the main screen and it was hard to determine which list was in which account. In iOS 13, things are more obvious, and you can group two or more lists together to avoid clutter.
Each account has a highlighted section in the new main Reminders screen just below the automated tiles above. That alone is exciting enough, but let's look at how grouped lists work.
Creating grouped lists
There are two ways to create a grouped list. First you can tap "Edit" in the upper right corner and then "Add Group" in the lower left corner. This will cause the New Group model to open, but before we get to that, we'll go the second way to start a new grouping.
Second, hold down one of your lists. To catch it, drag it over another list that you want to group it with, and drop it when the bottom list is highlighted. The Modal New Group should be opened.
You can only create grouped lists in iCloud, not in third-party services. So, if you have a Yahoo or Outlook section of lists that you want to consolidate, it needs to wait for those services to support it. Additionally, you can not drag a list from a service to a list in iCloud. Lists are kept in their own accounts.
In both cases, select a name for your list group in New group mode. You can then use the "Include" menu item to display the lists contained in the group. There you can remove some of the lists from the group (press the red minus button) or other lists you already have (the green plus).
If you want to change the order of your included lists, hold down the 3-button symbol on the right side of a list and drag it up or down to where you want it. When you're done, tap "Create" to exit.
View Grouped Lists  Your new grouped list will appear under My Lists (if you're just using iCloud for reminders) or iCloud (if you have more than one) associated account with reminders). The number to the right of the list indicates the total number of tasks for all lists in the group, not the number of lists. Tap the group's chevron to show or hide the lists it contains, and then tap any list to view your reminders.
If you hold down a grouped list, you can move it up or down drag to change their position in your lists. There are no nested grouped lists, so you can not drag and drop a grouped list to another list or grouped list. Within a consolidated list, you can do the same with nested lists to reorganize them.
You can also move the grouped list up or down by tapping Edit on the top right. Next, hold down the three-level icon and drag it to the new location. Press "Done" to complete the process. This also works with nested lists.