During cryptocurrency transaction and when receiving cryptocurrency coins we do make use of the wallet address which known as a special identifier that provide location to receive coins and the issue new traders or not expert In cryptocurrency faces or might face is mistaking another alphabet or number for another or capital alphabet use in the place of a small alphabet in which each letter carries his own identification and using capital letter where to use Small letter might cause your transaction fail or you will not receive your fund.
And also the alphanumeric must be complete and no one should missed ,so it might not cause failure in your transaction.
So that is why is advised to copy and paste the wallet address and send to the sender of the coin and not typed.