Why not just have a gigantic array that stores everything? It turns out it requires LOTs of storage.
Idea
Have a small array to store information
relatively small because it’s relative to the number of keys that you might have
Hash function
Converts the key into an index
Instead of directly using the key as index, we apply the hash function to the key first, and that hash function picks an index for us (like an index picker)
“scatters” the keys, behaves as if it randomly assigned keys to indices
Store key at the index given by the hash function
Do something if two keys map to the same place (should be very rare)
