The section in the middle is for twisty puzzles. This section is the most popular section since it has some of the most fun of the puzzles, which gave this verse its name.
There are other sections which feature other mechanical puzzles, and also paper and math puzzles, which are the hardest. These ones aren't as popular but still get well over 4 million visits per hour.
There is also a section that gives completely random puzzles for anyone to do. Statistics show that only 10% of the tries people do are successful. Even though this might be discouraging, sometimes perseverance helps and you can still solve a hard puzzle and be proud of it :)