Go with a dynamic website when

You want to sell products or services online
You want to interact with your users and offer them some online-services such as user-accounts, user rating and communities.
You want to provide different content to different users
You want to let users personalize the content or the layout
You want to give access to more people who can edit the website with different permissions

Features of a dynamic website

Websites design & Theme Development
Ability of adding unlimited content
Management of the members' list
Logged in visitors can review the content
Newsletters sending
Image Gallery
Contact form
Site-map
Basic tasks for web-site's security
Basic tasks for web-site's search optimization
100% Responsive (Device Friendly - Mobile, Tablet, Desktop etc.)