Plot3D[Cos[x+y^3], {x,-2,2}, {y, -2, 2}]

ParametricPlot3D[{(1+v/2*Cos[1/2*u])*Cos[u],(1+v/2*Cos[1/2*u])*Sin[u] , v/2*Sin[u/2]}, {u, 0, 2Pi}, {v, -1,1}, PlotRange -> {{-1.5,1.5},{-1.5,1.5}, {-1.5,1.5}} ]

ParametricPlot3D[{(1+v/2*Cos[1/2*u])*Cos[u],(1+v/2*Cos[1/2*u])*Sin[u] , v/2*Sin[u/2]}, {u, 0, 2Pi}, {v, -1,1}, PlotRange -> {{-1.5,1.5},{-1.5,1.5}, {-1.5,1.5}}, Boxed -> False, Axes -> False, Mesh-> None, PlotStyle -> Directive[Orange, Specularity[White, 10]], Lighting -> "Neutral"]

sfera[r_][u_,v_]:= r*{Cos[v]Cos[u], Cos[v]Sin[u],Sin[v]}

ParametricPlot3D[sfera[2][u, v], {u, 0,Pi} ,{ v, 0, 2Pi}]

ellissoide[a_, b_, c_][u_,v_] := {a*Cos[v]Cos[u], b*Cos[v]Sin[u], c*Sin[v]}

ParametricPlot3D[ellissoide[1,1,2][u, v], {u, 0,Pi} ,{ v, 0, 2Pi}, PlotRange-> {{-2,2},{-2,2},{-2,2}}]

iper1fa[a_,b_,c_][u_,v_] :={a*Cosh[v]Cos[u],b*Cosh[v]Sin[u], c*Sinh[v]}

ParametricPlot3D[iper1fa[1,1,2][u, v], {u, -2Pi,2Pi} ,{ v, -2Pi, 2Pi}, PlotRange-> {{-4,4},{-4,4},{-4,4}}]

pri[u_,v_] := {u, v, u*v}

sds[u_,v_] := {u, v, u^3-3u*v^2}

ParametricPlot3D[sds[u,v], {u, -1,1}, {v,-1,1},PlotRange-> {{-2,2},{-2,2},{-2,2}}]

torov[a_, b_][u_,v_] :={Cos[u]*(a+Cos[v]), Sin[u]*(b+Cos[v]), Sin[v]}

ParametricPlot3D[torov[3,7][u, v], {u, -2Pi,2Pi} ,{ v, -2Pi, 2Pi}, PlotRange-> {{-14,14},{-14,14},{-14,14}}]

ContourPlot3D[x^4+y^4+z^4-(x^2+y^2+z^2)^2+3(x^2+y^2+z^2)==3, {x,-2,2}, {y, -2, 2}, {z, -2,2}]

vn[x_][u_,v_] := Module[{xu, xv, N1},
xu=D[x[uu,vv], uu];
xv=D[x[uu,vv], vv];
N1=Cross[xu,xv];
Return[Simplify[(N1.N1)^(-1/2)*N1] /. {uu -> u, vv -> v}];];

vn[sfera[1]][u,v]

vn[sds][u,v]

ParametricPlot3D[vn[sds][u,v], {u, -1,1}, {v,-1,1},PlotRange-> {{-2,2},{-2,2},{-2,2}}]

Show[{ParametricPlot3D[sds[u,v], {u, -1,1}, {v,-1,1},PlotRange-> {{-2,2},{-2,2},{-2,2}}, Mesh -> None, PlotStyle -> {Opacity[.4]}], ParametricPlot3D[sds[u,v]/. u -> 1/2v, {v,-1,1},PlotRange-> {{-2,2},{-2,2},{-2,2}}, PlotStyle -> {Red, Thick}]}]

pt[x_][u0_, v0_][u_,v_] := x[u0,v0]+D[x[uu0, vv0], uu0]*u+D[x[uu0, vv0], vv0]*v /. {uu0-> u0, vv0 -> v0}

Show[{ParametricPlot3D[sfera[1][u,v], {u, 0,Pi},{v, 0, 2Pi}], ParametricPlot3D[pt[sfera[1]][0,0][u,v], {u, -.4,.4}, {v,-.4,.4}, Mesh -> None]}]