Bookmarks are the perfect way to save a search result for later. Unlike collections, they're not organized, and you're able to search on all your bookmarks directly from the bookmarks interface.
Bookmarking an item
Just like with collections, you start by clicking on the Bookmark & Collections button:
And then click on Bookmark:
A bookmarked item will appear with a "dark flag" icon on your search results:
To remove the bookmark, click again on the same button, and then on Remove Bookmark
Accessing all my bookmarks
You can see and search on all of your bookmarked items via the Bookmarks page.
Open it using the top left menu:
Once in the bookmarks page, you can see and search on all your previously bookmarked items:
You can also filter them using the Refine panel. Just click on the button right to the search box, and then filter your results as you would in a normal search.