You Don’t Use Two-Factor Authentication
Even strong and secure passwords are not enough. Many tech companies like Apple employ a technology called two-factor authentication. Your password is one of the factors used to authenticate who you are – but if someone else knows your password, they have access into everything in your account. That’s where the second factor comes in to play. In most cases, the second factor is your cellphone number.
With two-factor authentication turned on, anytime you attempt to log in to your account, make a major account change, or use your account on a new computer or phone; you’ll receive a text message with a temporary code to enter into the website you’re attempting to log into. This helps ensure that it’s actually you logging in, and not some hacker.
What to Do: Turn on two-factor authentication for all compatible apps and services, like your Apple ID.