Well, this is a often asked question. Which file type should I have my image be, and what is the difference. Well, this will tell you which ones. Now, I am going to only cover the four most commen file image file types. Jpg, gif, png, and bmp. There are lots others, but those are not as commen, and are best to stay away unless you know what you are doing(and if you knew what you were doing, you would not need this, now would you? ;) )

JPG:
This is one of the most commen used file types. This is great for photos because it has all the colors as part of the file type, and is able to handle very detailed and complex images. But, you can not make animations or have transparent parts with jpg. And if you have a simple image. Say, one that only has about 20 colors, then it is a lot larger then the gif would be because the jpg has the information for those 20 colors, and also has the info for the rest 16 million colors that is not used.

GIF:
This file type is right up there with JPG as one of the most commen file types. GIF does not have a set color palate. Unlike the jpg which has all the colors already in it, the gif creates the information for only the colors that it uses. But, because of that, the information for each color is a lot larger then in the jpg. So, if you have a image with a ton of different colors, and is very complex, if you save it as a gif, it will be a massive file size. But, if the image has only 20 colors, it is going to be extreamly tiny, because it only has the info for those 20 colors, and not the whole package. GIFs can also be animated, and are able to have transparent spots.

PNG:
This file type is not used too often, but it does have it's uses. It is a very large file type, and is best not to use very often. But there is one thing it can do that the others can't. It can make, not only just 100% transparent spots like the gif, but it has support for all Alpha colors. That means, you can have a color that is 50% transparent. If you attempt this with a gif, it will put a white area around and under that 50% transparency. But not with png. But it is not good to use png for any other uses, because it is a preatty large file type.

BMP:
Well, this one is used by windows alot because it is compleatly lossless. It is the most detailed of the four file types, but it is also the largest. It is best to stay as far away from it as you can. You can not have any Alpha colors(transparent), no animations. Nothing like that. It's just really really huge and detailed. But, it is used often with programs, like with skins and other things like that for programs on windows. Other then that, there is no real use for it.

Nice tut, really helps newbies. :headbang:

Heh, thx.

First(and almost only) real big tut I've really done.

And, it's simple, but has what everyone should know before they start making images.