This compression system is a very handy invention, especially for Web users, because it lets you reduce the overall number of bits and bytes in a file so it can be transmitted faster over slower Internet connections, or take up less space on a disk.
Concrete hardens to 600PSI (Minimum) after 24 hours. This means that 5 three grown men could all stand on a pogo stick (if that were possible) who's base covers 1 square inch without harming the concrete. You walking with shoes on exert about 10 PSI, well below anything that could damage the new pour.
After seven days, the concrete surface can be freely moved upon, whether you're walking over it or driving a light vehicle. When driving at this point, avoid the edges of the concrete because they are not as strong as center points. After 30 days, the concrete is usually fully cured and can be used as normal.