When a search view's Used for field value is Object Collection, you may subscribe users to that collection. As shown in the General Tab on Search View Screens image, when subscribing, you can choose to subscribe all users, or to subscribe users from a specific user group from a drop-down list.

General Tab on Search View Screens

Click the Subscribe link to apply your selection. You may also click the Unsubscribe link to remove the selected groups from that collection's subscription.

You can select multiple groups at the same time in the drop-down list when you are subscribing or unsubscribing. Additionally, if you add new members to a group, they are automatically subscribed to all assigned search views.

When you select All Users and then click a link, you get a warning that subscribing or unsubscribing all users might take a long time. Click OK in the warning box to continue the subscription process.