Google Earth^® allows creating KML files, that may be used to show point locations, line arrays, polygons or bitmaps on top of Google Earth´s satellite image surface.This is a very easy way of showing sample locations, "georeferencing" (or maybe google-earth-referencing, since the georeferencing of the GE satellite images is not always precise) a geological map or just showing a friend where you live or where the BBQ tonight will happen...

The below file is an example of a small kml file to display a standard placemark icon at a specific place and center the GE view at a certain height (range in m). The necessary kml-file elements are marked in blue (tags) and brown (user data)
dark blue means optional.

minimum kml file for placemarks

multiple placemarks in one file

overlay maps on Googles Earth

defining buildings in a kml file

fix if kml-files from your server do not open in GE

watch and play route in Google Earth

fix if Google Earth does not connect  to server

 <?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
  <Document>
  <Placemark>
   <name>my office</name>
   <LookAt>
      <longitude>8.853193712983327</longitude>
      <latitude>53.10919982492059</latitude>
      <range>500000</range><tilt>0</tilt><heading>0</heading>
   </LookAt>
   <Point>
     <coordinates>8.853193712983327,53.10919982492059,10</coordinates>
   </Point>
  </Placemark>
 </Document>
</kml>

xml declaration header
kml tag, opens Google Earth^®
Document tag opener
Placemark tag opener
name is optional
LookAt (not lookat! kml is case sensitive!):
defines the location, height and angle of the viewpoint.
LookAt is optional. Nice to define a view height (range, in m), tilt angle (degrees from vertical view) and heading(degrees from North)
Point tag. A Placemark could also be a string of lines (LineString) or a Polygon.
the Point location is defined by longitude and latitude in decimal degrees and height in m. Western longitude and Southern latitude are written as negative degrees

You can easily create such a file by using Google Earths Add - Placemark function or just click on the icon with the pin in the lower right. GE will put a Placemark in the center of your screen. You can grab it with the mouse and move it into the right place. You should also give it a short name. To save it, use File Save As.. I suggest to use .KML as a file format, since you can look at it in an editor, and easily see and understand how the KML syntax works. Often its easier to do some changes directly in the KMLfile.

The default option .KMZ is a zipped format.