1. Go to Discover.com/Activate using a web browser.

2. Log in with your Discover username and password (or create an account if you don't have one).

3. Enter your 16-digit card number, expiration date and security code.

4. Verify your identity by providing requested details such as your Social Security number (SSN) or security answer.

5. Click the "Activate" button to complete the process.

6. Your card is now ready to use for purchases, online transactions and rewards.

7. Alternatively, activate via phone by calling the number on your card or through the Discover mobile app.