.jpg artifacts are created when you overcompress an image file when saving a Bitmap (bmp) image in a paint program using the JPeg format to decrease the file size. You will see the artifacts as blocky areas especially between the transition of two colors. Here is an extreme example.

This is not my "second childhood". I'm not finished with the first one yet.

Time flies like an arrow; fruit flies like a banana.

"I'd like to die peacefully in my sleep like my grandfather....not screaming in terror like the passengers on his bus." - Jack Handy