As with any database, LUNA can easily be searched by keyword and works much like in a search engine, so you can use the AND, OR, NOT, and "" to help refine your search.
Use wildcard characters like "*" and "?". For example, enter "Par*" for results like Paris, Parigi, Paraguay, etc. Enter "Rom?" for search results like Rome and Roma.
Click on the carrot next to the keyword search box to open the advanced search. When you save a search you can make this search appear in a quick list in the search filters section of the Library, as well as the "Load Search" menu.
In addition to being able to search by a specific data field you can also search by label, owner of label, batch and other criteria. This "other criteria" includes starred, un-starred, draft, unlinked media, unlinked record, linked media, linked record, public Independent Media Items, private Independent Media Items, records, media items, and whether or not the item or record is viewable in the LUNA Viewer.
After executing a search, click on "Save Search" to save that query. This is helpful so that you don't have to build the same search query over and over. When you select "Save Search" you'll be saving this as a search filter and can choose whether or not to have this search filter display in your quicklist, and whether it should be publicly viewable.
You'll find that saved search query using the "Load Search" pull down menu or in your quicklist to the left of the Library thumbnails where the other filters are (All, Drafts, Starred, In LUNA Viewer, Batches, Labels).
To manage these saved searches click on "Manage Saved Searches".