How does compiling happen only for the first time in projectless development?

I read these words in a book:

Projectless development simplifies debugging: When creating a web project, you must recompile the entire application when you change a single page. With projectless development, each page is compiled separately, and the page is only compiled when you request it for the first time.

How d开发者_开发百科oes compiling happen only for the first time in projectless development? Should it recompile every time I run the page to reflect the new code I wrote it?

IIS compiles it. When a page changes and is uploaded again, IIS will compile it again.

See this topic on MSDN, in particular the section headed Automatic Compilation.

This should apply to other web servers as well (XPS, apache with mod_mono) as can be seen in this article.