You can use a word processor such as Microsoft Word to create your documents, but the documents must be saved as plain text (.txt).
You can use an open source editor like w3.org/Amaya to create and edit HTML documents.
If you save your HTML documents as something other than text, for example, in MS Word format (.doc), Web browsers will not be able to process the file correctly.

Aptana Studio focuses on the JavaScript and other elements that allow you to create Rich Internet Applications. One of the things I really like is the outline view that makes it really easy to visualize the DOM. This makes for easier CSS and JavaScript development. If you are a developer creating web applications, Aptana Studio is a good choice.

One of the best editors on the market which is free is the editor offered by from Microsoft known as visualstudio.com. It is ideal for checking the syntax of existing JavaScript files. To make this editor compatible with PHP you need to have Composer installed on your machine and select the correspoding

Komodo Edit is my favorite text web editor. It includes a lot of great features for HTML and CSS development. Plus, if that is not enough, you can get extensions for it to add on languages or other helpful features (like special characters). It's not the best HTML editor, but it's great for for the price, especially if you build in XML. There are two versions of Komodo: Komodo Edit and Komodo IDE. Komodo Edit is open source and free to download and is a trimmed down version of the IDE.

Notepad++ is a free source code editor and Notepad replacement that supports several languages. Running in the MS Windows environment, its use is governed by GPL License.
Based on the powerful editing component Scintilla, Notepad++ is written in C++ and uses pure Win32 API and STL which ensures a higher execution speed and smaller program size. By optimizing as many routines as possible without losing user friendliness, Notepad++ is useful for coding CSS. When using less CPU power, the PC can reduce power consumption, resulting in an environment which is more efficient.