I'm getting a new Android. How do I move my chat history over?
Summary:

   Backup your chats on your old phone.
       Go to WhatsApp > [Menu Button] > Settings > Chat settings > [Backup conversations].
   Transfer your microSD card to your new phone.
       Please see below if your phone only has internal memory.
   Install WhatsApp on your new phone.
   Click [Restore] when prompted to restore your message history.

Note: You cannot restore chat history from any other phone type to Android, or from Android to another phone type.
Details:

You can transfer chats from one Android phone to another. To do so, please follow these steps:

   To start, make a back-up of your most recent chats.
       Go to WhatsApp > [Menu Button] > Settings > Chat settings > [Backup conversations].
   Next, transfer this backup to your new Android phone.
       If your phone has an external microSD card, take the microSD card out of your old phone, and pop it into your new one.
       For phones that have an internal memory / internal SD card (most Samsung phones have this), you will need to transfer the /sdcard/WhatsApp/ folder from your old phone to the same folder of your new phone. There are a couple of ways you can do this. You can use a file explorer or even transfer the backup files to your computer.
       If you are unsure about what kind of SD card you have, we recommend checking your phone specifications on your phone manufacturer’s website.
   Once you have safely transferred your backup, you can install WhatsApp on your new Android phone.
   During the installation process, WhatsApp will automatically find your backup and ask you if you would like to restore it. Once restored, your old chats will reappear, on your new phone.

Having problems with phone number verification? Check out this article.

Cheers,
WhatsApp Support Team