anything you want it to be!
Here is the link for earth's ecology http://www.ecology.com/features/earthataglance/youarehere.html
Google reported in 2011 that there were over a billion downloads of Google Earth. That includes downloads of the Google Earth desktop client, mobile apps and the Google Earth plug-in.
An API, is an Application Process Interface. Google Earth's API allows the embedding of Google Earth onto a webpage. Google Earth is used by millions everyday.
Yes
Google Maps and Google Earth are used in geographic information systems (GIS).
The following Google products (and services) can be used for Geographic Information System (GIS)-related activities:Google MapsGoogle Earth (including Google Earth API)Google Fusion Tables
Google Earth Blog is a site unaffiliated with Google used to detail findings and discoveries on Google Earth. It's main benefit is its ability to share content with other users.
neither
science:biology
In order to use Google Earth you need to download the application. There are versions of Google earth for all sorts of mobile devices available for download.
it is in the same group
google earth 3d is called google earth 5.0