So basically the Mikala's constant Km describes the substrate concentration, the x value at which the rate, the velocity of that enzyme's activity is exactly half of its maximum velocity, v max. So if Km is equal to the substrate concentration, then V Naught is equal to v max divided by two. So that's the meaning behind Km. Km basically describes the situation when exactly half of all the active sites are filled with the substrate. And we'll talk much more about that in the next lecture. Now let's move on to two and three.