What is Happening With My Blood?

Ive noticed whenever I get a cut that drips blood the blood separates into three different types of tissue. The first is clear (which I ume is white blood cells), the second is thin bright red liquid (which I ume is red blood cells and white blood cells mixed, but the third and final thing is odd. Is a darker red stretchy substance, and when I touch it it remains the same shape. It reminds me a bit of really thick snot, or phlegm. Does anyone know why this happens?