Many companies across the Web are providing support for secondary authentication. Some do this with apps like Google Authenticator, while others just use SMS. Essentially, both methods provide you with a security code that you need to provide in order to log-in to your account.
LinkedIn is currently offering SMS authentication only, and you'll need to enable it. Here's how to set it up:
- Open the top-right menu and click on Manage next to Privacy & Settings.
- On the tabs along the bottom-left-hand side, click Account > Manage security settings (bottom of the left column).
- Under Two-step verification for sign-in, click Turn On. Enter a reliable cell phone number and then click Send Code.
Enter the code you receive via SMS to log back in to the LinkedIn website.
Editors' note, June 12, 2015: This How To post was originally published on May 31, 2013, and has been updated to include new information.