To write HTML code, you don’t need a specific code editor. A notepad should be good to get start. However, using the regular notepad is a very bad idea for writing HTML code. I don’t recommend it you writing it on the regular notepad. You need an code editor for better writing experience that comes with syntax highlighter features. So you can clearly see and understand what you’re writing. Let’s see how the HTML code displayed on notepad.

The above code in the notepad looks nothing wrong right? But what about this?

This is better right? If you are a beginner of HTML, I would recommend you start with Notedpad++ instead of notepad to learn about how to write HTML code and writing the code get familiar with HTML tags.
But you are more advanced, Notepad++ would not be a good code editor for you. Please use others more advanced code editor like Sublime Text, Atom or even Visual Studio Code that comes with more tools to help you write faster and better code. I personally prefer of using Visual Studio Code once you get familiar of HTML.