A blob is a spot, drop, or a shapeless mass of something, You can't just put blobs of paint on your canvas and call it art!
Blob is often used interchangeably with glob or drop. You might top your apple pie with blobs of whipped cream, or put a blob of toothpaste on your toothbrush. And if your map appears to be just blobs of color, you might want to put your glasses on and look again. Blob first appeared as a verb in the 15th century, meaning "to mark with drops or granules," a close relation of bubble.