Thinkphp-why can I parse php code on the html page in the Thinkphp framework-php Tutorial

Today, I found an interesting example using the framework. I can directly parse the code written in the .html file in the thinkphp framework. But under normal circumstances, it is not necessary to Parse internal code only for files suffixed with. php? Does anyone know how the tp framework works? Thinkphpphphtml

This day, I used the framework to find an interesting example. I wrote it in the. html file in the thinkphp framework. The code can be parsed directly.
But under normal circumstances, it is not necessary to parse files with the. php suffix. Code?

Does anyone know how the tp framework works?