You are conflating two entirely, unrelated things. There are two ways that your camera can record your images. RAW simply records 1's and 0's with NO in camera processing of the information. RAW records and keeps ALL the image data that falls on the sensor. Jpeg is the other option and comes in several levels of compression. When you shoot jpeg, the camera does some non-removable "adjusting" of the image data. It will compress the data some (which involves in discarding some of the information originally recorded by the sensor). The camera will also apply some color correction (white balance) and some sharpening in jpeg. If you shoot in RAW you may have to apply some color correction (but since you have ALL the data, you can adjust white balance in post processing very easily) and in RAW you WILL have to do some sharpening in post processing. There a pros and cons to both RAW and jpeg.
Aperture, as you have been reading it on this thread refers to which exposure functions are set by the photographer and which are set by the camera. In Aperture (preferred) which is designated AV on a Canon camera, the photographer sets the aperture (F:stop) and the camera will choose an appropriate shutter speed for the light conditions and chosen ISO. The other primary choices are Tv which is Shutter preferred, in which the photographer chooses the shutter speed, and the camera will then choose the aperture (F:stop), Program, usually designated by a P, in which the photographer allows the camera to choose both shutter speed and aperture,and Manual, designated M in which the photographer chooses both shutter speed and aperture.
At any given ISO it takes a set amount of light striking the sensor to achieve a correct exposure. As the ISO goes up, the sensitivity of the sensor also increases. Double the ISO from 200 to 400 and it takes half as much light to give you a correct exposure. Double it again to 800 and you halve the necessary amount of light again, and so on.
To achieve that correct exposure, the camera has two controls. The shutter speed determines how long the sensor is exposed to light, and the aperture determines how big a hole the light passes through. Aperture is exactly what it sounds like, an opening in the center of the lens. The opening consists of moveable blades which can constrict of open up to decrease or increase the amount of light that passes through the lens in a set period of time. F: numbers are the denominator of a fraction with "1" being the numerator and when you move across the aperture scale by a whole stop, the area of the opening changes by a factor of two thus either letting in twice or half the amount of light in a given amount of time. Whole F:stops are 1, 1.4, 2.0, 2.8, 4, 5.6, 8.0, 11, 16, 22, 32...... Change from F:2.8 to F:4 and the aperture will allow 1/2 the light through in a given amount of time.
The shutter opens and closes to expose the sensor to light, much like you would open or close shutters on a window to either let light in or block it out. Shutter speed is expressed as whole numbers (15, 30, 60, 120 for example) which are actually the denominator of a a fraction where the numerator is "1" and refer to a fraction of a second, thus a shutter speed of 120 is, in fact 1/120, so the larger the number, the less time the shutter is open. The shutter and aperture act in opposition to achieve a correct exposure. By that I mean that IF your correct exposure is 250 (actually 1/250) at F:8, you get the same amount of light striking the sensor at 1/125 @ F:11, or 1/500 @ F:5.6
Clear as mud??
Sorry, Todd and I must have been typing at the same time.