Understanding Nikkor Lenses?

I'll be buying the Nikon D5100 but am a bit worried about the lenses
Let's say I wanted to buy a new lens later on, would any nikkor lens fit perfectly?
What if I wanted to buy a 75-300 f/4 which must be gigantic. Would it fit?

I'd appreciate if someone professional could explain further about lenses' dimensions.

Added (1). Awesome! Very helpful. What about the filters? I see there are 52mm and larger diameters also. What does this value depend on?

I want to know too.

Virtually 99.99% of the lenses ever made by Nikon will fit your camera.

If the lens is a Nikon "F" mount, it will fit.

Virtually every lens in the current Nikon catalog will fit your camera.

However…

Your camera - being an entry level DSLR - will only be able to autofocus AF-S lenses. These are the newest Nikon lenses, and even though some AF (that is, not AF-S) lenses are still made today, you will not be able to autofocus them.

However, even the AF lenses will work on your camera, you will just have to manually focus them.

And older lenses - those 30 years old or so, will still work - but you will have to use manual exposure on them as they were made before auto-mode cameras were invented.

But within those limitations, almost every Nikon lens made for a DSLR or SLR will work. There are a few exceptions for some old lenses made a long time ago - and those that will not work will be listed in your owner's manual.

Of course, that does not include the few lenses made for the Nikon 1 camera.

Overall, Nikon has done a good job in making sure older lenses are compatible with new cameras (unlike Canon - which forced you to buy all new lenses if you owned a SLR in the '80s).

Lenses are primarily cataloged according to their focal length. Here is a web page showing what the different focal lengths look like:

http://www.althephoto.com/concepts/lenses.php

Note that in the DSLR world, some lenses are zoom, and some are fixed focus (that can't zoom). Fixed focus lenses are the choice of the most critical photographers as no zoom can match a fixed focus lens for it's optical quality. But zooms are more convenient for the masses. Just realize that in the DSLR world, you have your choice of either type lenses.

The other predominant lens characteristic is the "speed" or maximum aperture of the lens. A lens that lets in more light does so because it has larger diameter optics, and is said to be a "fast" lens. Since these lenses let in more light, they are useful for action photography as well as low light conditions.

To recap - the only thing your really need to remember is that for the modern lenses available today in the Nikon catalog, just remember that the D5100 will only autofocus AF-S lenses, not AF lenses. You can use AF lenses if you don't mind manually focusing them.