Posting key: this key comes into play when logging in, it allows posting, voting, commenting and other social activities.

It is used when trying to recover a lost account.
Memo key: it is used for the encryption and decryption of memos.

Hello @onyekachi08, please can you put these different sections above in your own words. It not a good practice on the steemit platform to copy and past.

Edit your work to show you understood the different key functions.

Thanks