It may be difficult to remember the phone number and type it in the WhatsApp message box if you want to share a contact number with someone. A contact may have email ids and multiple phone numbers.
Imagine the to and from rounds you have to make to share a contact. WhatsApp has made it really simple. You can share a big contact with multiple details in one go.
How to share a contact on WhatsApp?
Go to the phone contacts book on your smart phone
Pick a particular contact you want to share
Tap on share option
Pick WhatsApp from the multiple share mediums such as yahoo mail, Messages, Bluetooth, Messenger, etc.
Pick the contact or search for the contact you want to share
Tap on send…