This paper is written in an academic style but is practical in nature, suitable for students, researchers, or hobbyists.
Understanding the legal side of will keep you out of trouble. google earth airbus free
Airbus has a platform called OneAtlas. It is mostly paid, but they offer a "Free Trial" or "Sandbox" mode that allows you to search their archive. You can view thumbnails of high-res shots, but you cannot download the full file. This paper is written in an academic style
Tracking illegal construction or infrastructure degradation. suitable for students
While technically run by the EU (ESA), Airbus builds many of the sensors. You can view Sentinel-2 imagery (10m resolution) for free. It is less sharp than Google Earth, but it updates every 5 days.