by Khamosh Pathak

WhatsApp on Android and iPhone directly integrates with your contact book. As long as a contact is on WhatsApp, they’ll show up in the app. But you can also quickly add a contact to WhatsApp directly in the app.
How to Add a Contact in WhatsApp on Android
If someone hands you a business card and you quickly want to get the conversation started in WhatsApp, add them as a contact directly in WhatsApp. When you do this, the person’s information will be synced to your contact book (and to Google, depending on your settings).
To do this, open the WhatsApp app for Android, go to the “Chats” section, and tap the “New Message” button found in the bottom-right corner.