Let the user log in and log out is an easy way to provide good user experience.

https://drive.google.com/drive/folders/1hhIPL-XkvTYY-JhLslN6R19flNl5TAHa 

Header and footers are great for maintaining design consistency. 

https://drive.google.com/drive/folders/1I12kDZe7bVA80rinL7YEO7XpUtP8qfO6 

A slideshow banner draws your visitors attention to the featuring items in your website.

https://drive.google.com/drive/folders/15jNbP3l8u69JQm-04HDHV9E5H7oYoQD1 

To show information to the visitors, your webpages might need to connect to a database to retrieve or update information.

https://drive.google.com/drive/folders/1j5FT3UM6ttZ3Etez324_82pu9xE80cpa