Visualforce is not only a powerful way to create entirely new pages for your application, but also augments the Salesforce UI in multiple places. As we've seen so far, you can use it to extend the standard UI layouts and add custom buttons. Here is a list of platform areas that accept Visualforce pages:
- Layout sections
- Custom Buttons
- Custom Tabs
- Custom Tab Splash page
- Chatter Custom Publisher Actions
- Sidebar component
- Dashboard component
- Lightning pages
Profiles and Permission Sets also reference Visualforce pages; users must be given access to a page before they can use it from these areas.
Notice how the list of areas where Visualforce pages can be used differs from the list in the previous section. This is because Visualforce really relates to the Salesforce Classic user experience. Salesforce is focusing more and more on the Lightning Experience user experience and, thus, the aforementioned aspects are really only relevant if you plan to support both this and Salesforce Classic for your users. If you do, you may want to carefully consider if you need full parity between your features or if you want to leverage the fact that your application is more powerful when running within Lightning Experience to encourage your customers to adopt it.