Summarize:

. Fondant is a smooth, easily molded covering used to cover the whole cake or to make cake toppers. You can make it yourself or purchase ready-made fondant to save yourself the trouble.  Some brands of fondant tear more easily than others. Fondarific, Duff, and FondX are good beginner options.  Fondant dries quickly, so keep any portions you are not currently using wrapped in plastic or in the original container. Make this as smooth as possible to prevent wrinkling or tearing the fondant, which will go over the buttercream. See the icing section for tips.  Ganache can be used instead. It may be more difficult to smooth, but will provide a more stable base. Sprinkle cornstarch or spread shortening on a clean surface to prevent the fondant from sticking, then knead it for a couple minutes or until pliable. Knead by pushing with your flat palms and heel of the hand, to avoid trapping air bubbles in the fondant. Skip this step if you purchased ready-to-use rolled fondant. Use a rolling pin to roll the fondant out to a ¼ in (6 mm) thickness. Occasionally rotate the fondant by sliding your hand underneath it to the center, to make sure it hasn't stuck to the table. If you plan on covering a circular cake with fondant, you'll need a circle as wide as your cake's diameter plus twice the cake's height. Once the fondant is rolled out, roll it around the rolling pin, then unroll it again over the cake to drape it over. Use a flat tool – or your hands if necessary – to smooth the top surface and remove air bubbles. Next, smooth out a full circle around the top of the cake's sides, to make sure the fondant is firmly attached. Smooth the rest of the sides, gradually moving around the cake, until it is fully covered. Cut off the remaining fondant with a utility knife or pizza cutter. If you are covering a cake with an unusual shape, put the fondant in the same mold you used for the cake, let it harden slightly, then place it over the cake. Large cakes may need to be covered piece by piece, then repaired as described below. You can easily make two-dimensional fondant decorations by cutting shapes out with a utility knife or scissors. Use fondant in multiple colors to make faces, animals, or any shape you like. It can also be sliced into strips and arranged to form ribbons or a spiral flower. Three-dimensional shapes can be sculpted just like clay, although fondant is best suited for small cake toppers, since it dries quickly. Fondant can tear, crack, or bulge fairly easily, especially when used to cover an entire cake. Here are a few ways to repair these imperfections:  Put a small amount of new fondant into a bowl and mix in water ¼ tsp (1 mL) at a time until you get a toothpaste consistency. Spread this with a flat spatula over cracks or dents to make them smooth, then wait for them to dry. If the fondant cracks before you've started decorating, knead in some shortening or glycerin. Hairline cracks can sometimes be smoothed out with your fingertips, or disguised with a brush of shortening. A bulge is usually an air bubble. Try pricking it with a pin, then smoothing out the fondant.
Make or buy fondant Start with a smooth layer of buttercream. Knead the fondant. Roll out the fondant. Cover the cake (optional). Make fondant decorations. Repair fondant. Finished.