It's all about the pixels!
**IMPORTANT** Take a minute to read about pixels! They are at the core of your digital image.
How many pixels an image has will determine it's size and how it looks. Industry printing standard for an 8x10 image is 3000x2400 pixels at 300dpi (dots per inch, or ppi - pixels per inch).
Now let's say that the photo you see on the bottom came out of the camera at 3500pixels (a little larger than 10") and I cropped it to the face - it now might have a print quality of about 1"-2" (800 pixels) - so, if you purchase it, but want an 8x10 of that face, what a computer does is tries to read the color of the pixels closest, then fill those in to get back to that 3000 mark - now it is blurry and what is known as "pixelated" edgy or jagged.
Now you have compression! Everytime a .jpg image is opened, edited and resaved, it compresses a little more, degrading the quality. The internet will also automatically compress an image for faster loading. So, if an image doesn't look good on the internet, I guarantee it will be bad when you get it! That is also because of sizing, when made smaller on the internet, pictures pixels will compress and it might look better - but at full size, garbage!
If your show photographer sells through SmugMug - Look for these things!! When you are viewing an individual photo, in the bottom right corner you will see the top image for buying, sizing etc. Note the area circled in yellow - an "i" for info! Yes, click on that and the bottom box will appear telling you all about that photo! Note on the bottom image underlined "size" 702x914. So this photographer is selling this image as an original download for $26 and prints up to 5x7 - yet this image is barely 3"! This is why knowing about pixels is so important!! Check out image samples here.Back to everything you need to know about purchasing digital photography.