For some time now, WhatsApp has offered the functionality to back up all your chats and media in case you change (or loose) your smartphone. This is automatically done once every few days/every week in most cases, but you can also make a manual backup if need be.
To manually back up your messages on iOS, open the WhatsApp Settings menu and tap Chats > Chat Backup and tap ‘Back Up Now’ (select ‘Include videos’ if not already checked too). The backup should begin shortly after. It’s slightly different for Android users – head to Settings > Chats > Chat Backup and tap ‘Back Up’ to create a backup via WhatsApp servers, or log in with your Google account and backup via Google Drive.
To restore chats directly from a backup for whatever reason, simply uninstall and reinstall WhatsApp. When you open the app after the reinstall, you should be prompted to restore your most recent backup. Read next: How to restore chats from a backup
