Holy wow. Talk about your loaded question.
I don't think any one article can provide the 'necessities' of a successful website. If it was that easy, everyone would have successful websites!!!
Choosing the elements needed will greatly depend on the users needs, available content, and many other attributes. Here's an article that might help clarify what's important when it comes to a User Centered Design approach...
Asktog.com Article: First Principles of Interaction Design
Then... to make it a successful site, really will depend on what the measuring stick for success is and how the design is driving to meet the line.
Here's a case study of a bank that adopted a UCD mindset, and explained the results.UX Booth Article: Banking on Success: A Content-centered RedesignHere are a couple more articles that I think would really help get someone into the UCD mindset...UXMatters Article: Home Page DesignUXMatters Article: Building trust on ecommerce home pagesSpeaking of banks, here's a somewhat negative article (but may carry some truths that might feed into the conversation)...
I'm interested in what your take is on this topic. Please feel free to contribute your thoughts!
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