css3 - Webkit Gradient syntax -

I am reading about property and I do not understand is .

Radial:

  -WebKit-Gradient (radial, 105 105, 20, 112 120, 50, from (# FF 5f 9 8), (RGBA (255, 1,136), 0)), color-stop (75%, # ff0188),  105 105, 20, 112 120, 50  what does  

p >

linear:

  Background: -WebKit-gradient (linear, 40, 50, 50, color-stop (0.0, yellow), color-stop (0.5, orange) Stop (1.0, red));  

What does 40 50, 50 50 mean? For the radial slope, the first two logic represent an initial cycle with the original (x0, y0) and radius r0,

for linear: "40 50, 50 50", 50 up to 40px The px starts at the top, and 50px is left at 50px.