What is length contraction in special relativity?

[MadisonBG]

I've been studying special relativity and the concept of length contraction keeps coming up alongside time dilation. How does special relativity length contraction work? If something moves close to light speed, it appears shorter in the direction of motion. But is it actually shorter, or just appears that way? How does this relate to the relativity of simultaneity? And what are the practical implications, if any?