Most of it comes from businesses decommissioning their IT assets, but we also accept people walking in to drop things off. Most of that is "certified", meaning that we go through everything they dropped off, remove the drives, scan serial numbers, and ensure data on the drives are destroyed (either by physically destroying the drives, or overwriting them[0]). Laptops with sufficiently high specs are stacked on pallets in the warehouse area I work in, where it becomes a sort of free-for-all with my 3 co-workers there. Most of what we have is 5 to 10 years old, but sometimes there's the occasional retro piece, or electronic equipment that isn't a computer, like radars, lidars, or A/V stuff. I've been excited to pull out a laptop with a recent 14th gen (or so) Intel Core CPU, only to be let down when I discover it has a broken screen or is unbootable.