Summary: The ten most egregious offenses against users. Web design disasters and HTML horrors are legion, though many usability atrocities are less common than they used to be.
Since my first attempt in 1996, I have compiled many top-10 lists of the biggest mistakes in Web design. See links to all these lists at the bottom of this article. This article presents the highlights: the very worst mistakes of Web design. (Updated 2011.)
1. Bad Search
Overly literal search engines reduce usability in that they're unable to handle typos, plurals, hyphens, and other variants of the query terms. Such search engines are particularly difficult for elderly users, but they hurt everybody.
A related problem is when search engines prioritize results purely on the basis of how many query terms they contain, rather than on each document's importance. Much better if your search engine calls out "best bets" at the top of the list — especially for important queries, such as the names of your products.
2. PDF Files for Online Reading
Users hate coming across a PDF file while browsing, because it breaks their flow. Even simple things like printing or saving documents are difficult because standard browser commands don't work. Layouts are often optimized for a sheet of paper, which rarely matches the size of the user's browser window. Bye-bye smooth scrolling. Hello tiny fonts.
Worst of all, PDF is an undifferentiated blob of content that's hard to navigate.
PDF is great for printing and for distributing manuals and other big documents that need to be printed. Reserve it for this purpose and convert any information that needs to be browsed or read on the screen into real web pages.
> Detailed discussion of why PDF is bad for online reading
3. Not Changing the Color of Visited Links
A good grasp of past navigation helps you understand your current location, since it's the culmination of your journey. Knowing your past and present locations in turn makes it easier to decide where to go next. Links are a key factor in this navigation process. Users can exclude links that proved fruitless in their earlier visits. Conversely, they might revisit links they found helpful in the past.
Most important, knowing which pages they've already visited frees users from unintentionally revisiting the same pages over and over again.
These benefits only accrue under one important assumption: that users can tell the difference between visited and unvisited links because the site shows them in different colors. When visited links don't change color, users exhibit more navigational disorientation in usability testing and unintentionally revisit the same pages repeatedly.
> Usability implications of changing link colors
Guidelines for showing links
4. Non-Scannable Text
A wall of text is deadly for an interactive experience. Intimidating. Boring. Painful to read.
- bulleted lists
- highlighted keywords
- short paragraphs
- the inverted pyramid
- a simple writing style, and
- de-fluffed language devoid of marketese.
> Eyetracking of reading patterns
5. Fixed Font Size
CSS style sheets unfortunately give websites the power to disable a Web browser's "change font size" button and specify a fixed font size. About 95% of the time, this fixed size is tiny , reducing readability significantly for most people over the age of 40.