naturally, knives get dull from extensive use. commercial sharpeners can sometimes be pretty expensive. here's how to get a very cheap, if not free, and effective way to sharpen a knife.
Step 1: What You Will Need
a knife of course
a light filament-- you can get these at Lowes for a dollar or two. if you have street lights, then when they change them, you can go over and ask for an old one. they are just going to throw them out, so they will probably say yes.
Step 2: How to Sharpen
to sharpen your knife, take the filament and run it along the side of the blade. to this until it doesn't feel very gritty. some pressure should be applied.
Step 3: And Your DONE
your knife will literally feel as good as new and will cut like a razor blade!