The Fuzzy search attempts to enlarge the search by allowing the search engine to find words spelled nearly the same as the ones you entered. It does this by simple letter substitution. For example a Fuzzy search on "Macdonald" returns records with "McDonald" and "Macdonalds" as well. A Fuzzier search adds variations like "Donald."
Behind the scenes, records may have a range of dates that represent a known or reasonable guess about the years associated with a given object. The Fuzzy Date limits your search to records tagged with this class of dates. If you enter the year "1900" and for "how fuzzy?" select "+/- 5 years" the system looks for objects whose date range intersects with the period 1895-1905. If it was tagged with a date range of 1888-1898, for example, that record would be returned, as would records tagged 1880-1920 or 1903-1913. On the other hand, a record tagged 1906-1960 would not be returned.
The Geographic Location limits your search to records tagged with that specific place name. Some of the records in the index may not be indexed by place, and would not appear in the results. Sometimes, places are contained by other places (a bay in a lake, or a village in a township, or a "harbor" in a town). You will need to search each term separately. It is a powerful way to narrow results but use it with caution.
Keyhole Markup Language (KML) is an XML-based language schema for visualizing geographic annotation on two-dimensional maps and three-dimensional Earth browsers.
The KML file specifies a set of features (placemarks, images, 3D models, textual descriptions, etc.) for display in a KML application. The most common of these is Google Earth, but there are a number of other 3D earth browsers and viewers which implement the KML encoding.
Each place located by the KML file uses a minimum of a longitude and a latitude. If additional data is provided, the view can be more specific — for example a "camera view" uses further details such as such as tilt, heading and altitude. Enriched KML files are often distributed as KMZ files, which are zipped KML files with a .kmz extension. When a KMZ file is unzipped, a single "doc.kml" is found along with any overlay and icon images referenced in the KML.
The first step to using any KML file is to have an application or browser plug-in which is capable of handling this file format. We'll use Google Earth as the example here.
When you click on link to get a KML file for the first time, your browser may not know how to handle this file format, and will simply offer you the opportunity to download it. This means you'd then need to locate the .KML file on the computer's desktop (or wherever you have set the default download folder to be) and double click on that file to launch Google Earth.
Excellent Google Earth Help files and documentation are available.