Now, look at this here. Let us take an area on the ocean surface, some area. The waves are of various types; I mean, there is a wave picture; it is changing. You have a stick here measuring; it is changing continuously. It goes like that whatever, continuously. But, the question is like this – how did the wave get generated? Before that, let me tell you this aspect – the energy average of the wave per unit square area – what is this? It is half rho g A square; it depends on amplitude square. Now, the second part, wind is blowing over this (Refer Slide Time: 15:00). Normally, these are because of wind generation; wind is blowing over this. For a long time, the wind is transferring certain energy to the surface. Now, the wind has been blown for such a long time that whatever it could transfer has been transferred, which is what we call