Common term for the process of signing up or creating an account on a website, app, or service.
User registration is required to use this site.
会員登録 specifically means 'membership registration', often implying a more formal or ongoing relationship, while 利用者登録 is a broader term for any user registration.
新規登録 means 'new registration' and is often used as a button or link label, whereas 利用者登録 refers to the overall concept of user registration.
Compound of 利用者 (user) and 登録 (registration).