Highlighting is a way to mark caches. You can highlight a cache from the Cache Details screen, from the Live Tab, and from an map of caches in Offline Lists. You can also use the long press option to long press on a cache in List View or the cache map callout to show a menu that includes Highlight.
When you tap Highlight you will see a list of 20 colors that you can select from. Tap the color you want and the cache will be highlighted with the color you selected. The selected color will appear as a bar down the side on the Cache Details screen, on the left side of the cache in List View and the map icon will have a small bar in the same color.
If it appears as if your highlighting is out of sync, go to the More... tab->Highlighting and choose "Manually Sync Highlights"
If a highlighted cache is deleted then that cache continues to be tagged in the cloud for highlighting. If you view that particular cache again it will be highlighted. You can, of course, delete a highlight at any time.
You can edit the label of the highlight so it means something to you rather than just having the label as the name of the color. You can delete highlights on all caches by color or even all of the highlights you have.
Syncing Using iCloud
Highlighted state of every cache will be synced across devices if those devices are logged into the same iCloud account. If they are not, syncing will not occur.