How come when you put your memory card in your mac nothing happens?

When you insert a memory card into your Mac and nothing happens, it could be due to several reasons. The card may not be properly seated in the slot, or it could be corrupted or formatted in a way that the Mac doesn't recognize. Additionally, the Mac may not automatically open the file explorer, but you can manually access the card through Finder. Checking the card on another device can also help determine if the issue lies with the card itself.