Internet Explorer also still supports it. You can write a full, albeit basic, application in a text file, rename it as 'whatever.hta' and run it by double clicking on it. It launches in its own window using the IE html control as its form. The MSDN pages have a clone of Notepad.exe as a vbscript .hta as an example.

In some ways it's like the grandparent of Electron or React apps, just a decade too early.

The last .hta I wrote was several years ago - a [mostly] complete clone of 'Active Directory Users & Computers' that anyone could use.