please explain this code

x = 0:0.1:20;

mf1 = trapmf(x,[0 2 8 12]);

mf2 = trapmf(x,[5 7 12 14]);

mf3 = trapmf(x,[12 13 18 19]);

mf = max(0.5*mf2,max(0.9*mf1,0.1*mf3));

figure('Tag','defuzz')

plot(x,mf,'LineWidth',3)

h_gca = gca;

h_gca.YTick = [0 .5 1] ;

ylim([-1 1])

xCentroid = defuzz(x,mf,'centroid');

hCentroid = line([xCentroid xCentroid],[-0.2 1.2],'Color','k');

tCentroid = text(xCentroid,-0.2,' centroid','FontWeight','bold');

xBisector = defuzz(x,mf,'bisector');

hBisector = line([xBisector xBisector],[-0.4 1.2],'Color','k');

tBisector = text(xBisector,-0.4,' bisector','FontWeight','bold');

gray = 0.7*[1 1 1];

hCentroid.Color = gray;

tCentroid.Color = gray;

xMOM = defuzz(x,mf,'mom');

xSOM = defuzz(x,mf,'som');

xLOM = defuzz(x,mf,'lom');

hMOM = line([xMOM xMOM],[-0.7 1.2],'Color','k');

tMOM = text(xMOM,-0.7,' MOM','FontWeight','bold');

hSOM = line([xSOM xSOM],[-0.7 1.2],'Color','k');

tSOM = text(xSOM,-0.7,' SOM','FontWeight','bold');

hLOM = line([xLOM xLOM],[-0.7 1.2],'Color','k');

tLOM = text(xLOM,-0.7,' LOM','FontWeight','bold');

hBisector.Color = gray;

tBisector.Color = gray;

hCentroid.Color = 'red';

tCentroid.Color = 'red';

hMOM.Color = gray;

tMOM.Color = gray;

hSOM.Color = gray;

tSOM.Color = gray;

hLOM.Color = gray;

tLOM.Color = gray;