IDE stands for Integrated Development Environments, you may have heard of Dreamweaver, Visual Studio, Eclipse, Expression Studio and many others.
As new web technologies emerge and are adopted by modern browsers, software companies accelerate their iterations of such IDE’s and new tools to service developers and designers as well. Some are remarkably useful, others not so much. For me it all boils down to the style of working I have acquired during the years and which tools fit this style.
Is not my intention to write about which IDE is better, or enter into the discussion that web design or development should be done in xyz environment. Simply if you are starting web design or you are a few years into it already, then my advice might be useful to you. It might be useful because I asked myself the same question, and often struggled to find an answer which now I realize it would only come with time.
IDEs were good for learning.
What do I mean by that? The drag and drop feature you have, where you can drag an input control into your design window and then see you code window display <input></input>, along with setting properties for you elements in a neatly organized panel. Seen how these property get set in the code was like a teacher explaining it on a class. It might not work for everyone but it worked for me.
Back then there was not as many learning resource as today and I had to bootstrap my learning because I had to keep my full time job. I spent countless nights awake until 4 and 5am, with the old 24k connections doing my learning, followed tons of tutorials, searched for books on libraries, tried to emulate great web designs of the time. I never stopped feeding myself with information related to web design and IDEs were there all along with me.
Fast forward to today, I own Visual Studio 2011 and have a subscription to the Adobe Creative Cloud which gives access to Dreamweaver CS6. I rarely open them because now I hand code most of my work. I am not exactly sure when I transitioned from Visual Studio to Notepad++ but what I can tell you now is that I work much faster without the IDE, but better yet I have a better understanding of what is going on with my project. Sometimes I even skip the photoshop mockups and go straight from sketches to HTML and CSS.
In conclusion, the choice is up to you. If you are starting web design, my recommendation would be to go straight to code, whether with an IDE or not. You might need to know how to use them because employers have design and development environment setups where IDEs are the only way to go. Current resources like Treehouse.com, CodeAcademy.com, TutsPlus.com and many others offer great content to get you started. This is a subjective post based on my own experienced and obviously biased by my preferences. Good luck and keep learning.