A lot of times people will make the comment : ‘Your photos are so clear, mine never look that clear‘. Thank you but I assure you not all my photos are very clear. haha. I should post outtakes more often. But I think what you are referring too is a by product of correct exposure and making sure the shutterspeed is high enough that there is no blur caused because of a shaky hand.
Also, when photographers post photos on the internets, they usually sharpen them just a tad. When you resize a photo for the web, you need to sharpen it a little to simulate what the photo will look like in print.
Example 1: No sharpening, just resized for the web.
Example 1: Sharpened at 15%
Example 1: Way oversharpened.
You never want to sharpen so much that every strand of hair is visible.
Now go forth and sharpen with discretion.