Only few know that the Google Earth application was first originated as EarthViewer 3D and wasn't, in fact, developed by Google. At the time of its first release, it belonged to Keyhole, and only later, in 2004, it was acquired by Google. Since then it was enriched with fresh data, images and new impressive features for the users.
At the moment, there are three versions of the application: one for PC, a web-based one, and one for Android/iOS-devices. The PC version is available in different flavors: Google Earth (free), Google Earth Pro (for about $400) and Google Earth Enterprize.
First of all, the free version of this program allows you to travel around the globe visiting any country you wish and either view some photographs of memorable places alongside the information about them, or travel around the streets of a city via the Street View mode. The only drawback of the latter is that it is available for a limited number of cities. Still, if you want to have a tour around Paris or Berlin there won't be any difficulties. Besides, if the Street View is available for the city you are traveling to, you can use it like a 3D map to find your way around the city, or as a trip planner, making a video tour beforehand and following it later. Also, you can use this application to teach your kids the day-night change, providing visualization of the process, or to study together how the world looked some decades ago, using historical imagery.
Apart from our planet, you can travel around the space or visit other celestial bodies like Mars or the Moon. You can rotate and zoom them, view photos, read facts and trivia about them. There are lots of new things to learn about sitting in front of your monitor: the Moon, for example, features marks of expeditions and notable geographic places, like craters or hills.
Unfortunately, if you want to experience the full beauty and speed the application is capable of, you need a very powerful computer. If you do have one, you will get an unforgettable experience traveling on the three planets, or just around the space.