Late last year, Twitter added support for security keys in order to provide an extra layer of protection for your accounts and make it easier to sign in on Android and iOS, just like you can do on desktop. However, you needed to have another authentication method first such as SMS verification before you could make use of that security option.
That's changing now as Twitter announced today that you can use security keys as the only authentication method, without you having to turn on another two-factor authentication method. This means that you can use security keys as the only 2FA option on both mobile and the web; there's no need to add SMS or authentication code as backup.
In March of this year, Twitter teased the new option when it announced the ability to enroll and log in with multiple physical keys on both mobile and the web. Previously, the micro-blogging site allowed you to enroll only one security key.
Twitter also noted how important the new change is, especially to people who might not be able to have a backup 2FA method or does not want to share their contact number with the company. It also touted security keys as the most "effective way" to secure your account. The latest option is expected to bolster security for your account on mobile and desktop.