In an attempt to keep your account safe and secure, Twitter has launched two-factor authentication process. This process requires to enter your password, and then a six-digit code that will be sent through text message to your number, anytime you try to log into Twitter.
The two-factor authentication process prevents the account and its details from hackers and phishing attacks, which are growing worse now. Here's how you need to do it.
Go to your Security and Privacy Settings on and select the option "send login verification requests to my phone."
If you already don't have a phone number attached to your account, follow the prompts to add one.
Now you will receive a text message, verifying that you have the right number added to your account.
Once you receive the verification message, you are done with the process.
Now, when you log in to your account Twitter account next time, a six-digit login code will be sent via text message to your phone. Enter the code when prompted to access your account.