Designing a registration and login system involves ensuring security, simplicity, and a seamless user experience. Here's an overview of how I developed one using HTML, CSS, PHP, and MySQL:

1. User Registration: A form allows new users to provide necessary details and register. Their information is securely stored in a MySQL database.

2. Account Activation: Once registered, users receive an activation email with a verification link. They must click this link to verify their email.

3. Login Process: Verified users can log in and access the site. If a user tries to log in without verification, the system reminds them to verify by showing the date and time of the verification email.

4. Account Management: To enhance security, unverified accounts are deleted automatically if they remain unverified after a set period.

5. Access Granted: Upon successful verification, users gain full access to the website and its features.