ParametricPlot3D[{u*Sin[t],u*Cos[t],t/3},{t,0,15},{u,-1,1}]
ParametricPlot3D[{2*Sin[u]*Cos[v],2*Sin[u]*Sin[v],2*Cos[u]},{u,-Pi,0},{v,-Pi/2,Pi/2}]

DensityPlot[Sin[x*Cos[y]],{x,-10,10},{y,-5,5}]
ContourPlot[Sin[x*Cos[y]],{x,-10,10},{y,-5,5}]

pts1=Table[{Cos[2k*Pi/5],Sin[2k*Pi/5]},{k,0,5}];
ListLinePlot[pts1,Axes->False,AspectRatio->1]
pts2=Table[{Cos[2k*Pi/8],Sin[2k*Pi/8]},{k,0,8}];
ListLinePlot[pts2,Axes->False,AspectRatio->1]

a=1;
PolarPlot[Sqrt[a*Cos[2*theta]],{theta,0,2*Pi}]
PolarPlot[a*(1-Cos[theta]),{theta,0,2*Pi}]

ParametricPlot3D[{z*Cos[phi],z*Sin[phi],z},{z,-3,3},{phi,0,2*Pi}]
ParametricPlot3D[{Tan[u]Cos[v],Tan[u]Sin[v],Sec[u]},{u,0,Pi},{v,0,2*Pi}]