What the F is an F-stop!?

Lets talk about Apertures. all cameras have them. They are the hole that lets light hit the sensor. That aperture is either fixed, like on a cheap throwaway camera, or adjustable, like on all DSLRs and most point and shoots. By accessing your menu you can usually find an f-stop control. The amount of light hitting the sensor is important, but how long it hits the sensor is important as well. the shutter speed determines this. It is a delicate dance between the two that makes great photos.
The other thing that the aperture or F-stop is that it helps determine how much of a scene is in focus. You have probably seen cool pictures where the background is out of focus and creamy while the subject in the foreground is sharp as a tack. That is depth of field. The lower the number that your f-stop reads means there is less in focus in a scene, and you get that blurry background or foreground. The higher the f-stop say F 5.6 and above on a fixed lens, the more that is in focus. Once you get into zoom lenses the calculations get pretty nuts because zoom lenses can narrow depth of field as well. The blurred backgrounds created by low f-stop numbers are really cool and arty, but you do lose some sharpness in the photo. a good compromise is to take the lens either two up from the lowest number, or two down from the highest f-stop and those will be the best bet to get the sharpest picture. an easy way to do this on many cameras is the 'A' mode, meaning aperture priority. Then you chose the f-stop you want and the camera chooses everything else, like shutter speed.
When I get arty and nuts, like with my wheat picture, I want blurred backgrounds so I'll take a bit of softness. Likewise when I am shooting indoors or in poor light I crank the F-stop to the lowest number to let all of the light in that I can. My 35mm F-1.8 Nikkor DX lens is great for this. 1.8 lets in a ton of light. But of course my focus is very thin, like one of my cats eyes will be in focus and the other won't. so play around with it and find what works for you. It is fun!