Google Earth is a virtual globe program that was originally created by Keyhole Inc, which was later acquired by Google in 2004. It maps the Earth by overlaying satellite imagery, aerial photography, and GIS data onto a 3D globe. Google Earth was originally available under three licenses but has been reduced to two - a free version with limited functions and a commercial version called Google Earth Pro. It requires at least a Pentium III 500 MHz processor, 256MB RAM, 400MB disk space, and a 64MB graphics card to run effectively.