By Backup WhatsApp chat all the chat data will be stored safely in their respective google accounts. So if we access it in a new device or re-login with a cellphone that has been flashed again, all the old chat data will be displayed automatically again.
To do a backup please go to the Settings menu on WhatsApp, then select the Chat menu (backup, history, wallpaper).

Back up Chat tab to backup all chat data to your Google account

BACK tab to start Backup or Backup Data Chat

We can also backup WhatsApp Data Chat regularly whether it's Daily, Weekly and Monthly. So that the chat will automatically back up automatically if the cellphone is connected to the internet according to the time of the backup choice.

Here we can also choose data usage in backup, whether it only uses Wi-Fi if there is a Wi-Fi connection or a choice of Wi-Fi or cellular data.

We can also backup the chat data by clicking it through social media applications such as ChatWhats itself, email, share it and other share menus that are installed in the Android system.
Select the Export menu in Chat History to start sharing or sharing a chat data backup file

Select which chats you want to export or share


Select media share (backup) chat such as Email, WhatsApp or Bluetooth

The OK Tab Archive Confirmation message appears to continue
There are several methods that can be applied to Backup or Backup WhatsApp messages that are considered important so that they can be used or reopened when needed in the future.