You can add tags to your properties on the properties page to group them. This is helpful to increase organization by filtering. There is a limit of 5 tags per property.
To create a tag, click "Add tag" below the property address in Properties, type in the tag, and hit the button "enter" on your keyboard. It should be saved. To remove a tag, click the "x" icon next to the tag.
Many pages (channels, integration zone, properties, calendar, etc) allow you to filter by tag to focus in on a certain group of properties. This can increase efficiency and effectiveness when property counts are high. Instead of showing all properties on the page, you can set a filter to only show a subset.
Before filter (no tags selected) :
After filter with "test tag for Alcatraz" selected 😀