When you block someone on WhatsApp,
they will not be notified.
You will stop receiving messages and calls
from the contact you have blocked.
Even if they continue to send messages,
the messages won't show up on your phone.
Any messages they send
will show the message-sent mark on their end,
but not the message-delivered mark.
The contact you have blocked will no longer
be able to see your status updates or profile picture.
You cannot send messages or calls to this contact
unless you unblock them.
Here are some things that do not change
after you have blocked someone.
Blocking someone does not remove them from your contacts.
They will still show up in your list of contacts,
but you can remove them from your phone book.
Also, preexisting group chats will remain unaffected.
So if you are already in a group chat
with your blocked contact before you block them,
they can still contact you there.