This study is about learning how well a medicine called **etrasimod** works for adults with moderate to severe **Ulcerative Colitis (UC)**, which is a disease that causes swelling and sores in the colon. Patients will take etrasimod as part of their regular care if their doctor thinks it's the best choice and they've never used it before.

The study lasts for 52 weeks, plus a 28-day period to check on safety. Patients will fill out health questionnaires from their phone, tablet, or computer to share their UC symptoms. This will help doctors see how the medicine affects their condition over time.

Key Points:

• The study is 52 weeks long with an extra 28 days for safety follow-up.
• Participants will fill out health surveys online during the study.
• Participants must be adults (18-64 years) and should not have used etrasimod before.