The memory palace is a technique where you walk along a route you know really well and put memories in certain locations along the way.
For example, you could go through your childhood home and place the items from your shopping list on the kitchen table. Then, when you’re in the grocery store, all you have to do is mentally enter the kitchen and see what’s there.
Once you see tomatoes, onions, and potatoes on the table, you know what to shop for. You can even have multiple routes for different kinds of memories.