Understand the Web
Want to know if your ‘HTML application’ is part of the web? Link me into it. Not just link me to it; link me into it. Not just to the black-box frontpage. Link me to a piece of content. Show me that it can be crawled, show me that we can draw strands of silk between the resources presented in your app. That is the web: The beautiful interconnection of navigable content. If your website locks content away in a container, outside the reach of hyperlinks, you’re not building any kind of ‘web’ app. You’re doing something else.