When searching for free-licensed fonts for a project, I've found that a lot of fonts looks pale and thin on screen, unless enlarged to a very big size. Others are dark enough, but somewhat blurred. Theirs glyphs don't have homogeneous black color with sharp outlines which distinguishes them from the background.
At the picture above http://(at the file I've uploaded to this link it is much more obvious to see), only line 3 (DejaVu Sans) and 5 (Arial) are clear and sharp.Lines 1 and 2 are blurred, and line 4 is blurred and also not dark enough.
So I would like to ask what makes some fonts sharper then others, and weather making a font to look sharper on screen involved a lot of work.