An Experience designer can create user groups to send notifications and assign tasks to the whole group of users rather than each individual at a time.
There are two ways you can create a list: a static list where you select the names yourself. However, this won't add new people to the list. The other is by creating a list based on a filter value.
Fixed list of users
You can create a user group and add the existing users to the group. However, this won't add anyone new to the group automatically. You will need to add or remove people to or from the group manually.
You can choose an existing filter or create a new one when you add your new group. However, if you add a new filter, you must ensure you assign your users to the filter value so that they are included in the correct user group.
For example, if you have the onboarding template installed, you'll probably have an existing filter with the "Only Preboarder" value. A workflow assigns this value to new joiners automatically. After their start date, another workflow removes the value, which means the user would only appear in a user group with this filter before their start date.
You can remove any user groups not used in a workflow. If the group is used on a workflow, you'll have to remove it before you can delete the group.
Send notification workflow action
You can select any user groups when adding a Send notification workflow action and see this is the workflow history too.