There are two main types of camera in the high-end market today, mirrorless cameras and DSLRs. Each of these technologies has its own benefits and downsides. So, what is mirrorless camera technology, and is it better than a DSLR? Which should you buy?
What is Mirrorless Camera Technology? A mirrorless camera is one where the light goes straight through the lens to hit the CCD, which is the part of a digital camera that records the image. This technology was, until recently, reserved for lower-end point and shoot cameras, but it has improved a lot recently and today you can get high-end cameras which rely on mirrorless designs.
Contrast this with the DSLR - the traditional 'king' of cameras, which uses a mirror and a prism to direct light to the CCD. The mirrorless camera offers a good preview on its LCD display, but the viewfinder is slightly off, while on the DSLR what you see in the viewfinder is what you will get when you take the shot.
Which is Better? Which camera you purchase is now more a matter of personal preference - mirrorless cameras are smaller and very slightly lighter than DSLRs, although the weight difference is not really that significant.
DSLRS tend to offer better images in low light, because they all use phase detection, while a lot of mirrorless cameras use contrast detection (but this is changing too, as high end mirrorless cameras have started incorporating phase detection features). This means that they have fast and reliable auto-focus.
When you go to take a photo outside in good light, a mirrorless camera will offer a preview that is close to the final image, but in darker environments, or where you are taking images of fast-moving subjects, you will find that the mirrorless camera struggles to provide a good real-time preview. DSLRs struggle here too - they have an optical viewfinder, which is accurate, but the digital display will not be all that accurate.
Image stabilization on DSLRs and mirrorless cameras tends to be fairly similar, although sometimes the mirrorless model can be superior, because high end models will shift the lens element as well as the sensor to provide good stabilization. For smaller movements, this works very well - but for massive amounts of movement, the difference will not be noticeable between DSLRs and mirrorless cameras.
It is a good idea to test a few cameras, ideally in the kind of conditions that you will want to be taking photos in, to see what suits you best.