Twitter is finally bringing two-step authetication to accounts after a series of high-profile hacks. It is currently rolling out so you may not see the option just yet. If you do, first head over to settings, then go down to Account Security and check "Require a verification code when I sign in." After you sign in, Twitter will send a code to your phone that you'll need to input to access your account. Twitter will then generate a temporary password which you'll need to sign in on other devices or apps. This will make Twitter accounts much more secure, so we should hopefully see a much lower percentage of hacks in the future.