What is how to patch a hole in drywall?

Here's a guide on how to patch a hole in drywall:

Small Holes (Nail Holes, Picture Hanger Holes)

These are the easiest to fix.

Preparation: Clean the area around the hole. Remove any loose debris or paper.
Filling: Apply a small amount of spackle or drywall%20compound directly into the hole using a putty knife.
Smoothing: Smooth the compound over the hole, making sure it's flush with the surrounding wall. It's better to use thin layers than one thick one.
Drying: Allow the compound to dry completely according to the manufacturer's instructions. This typically takes a few hours.
Sanding: Lightly sand the patched area with fine-grit sandpaper to create a smooth surface. Be careful not to sand too much, or you'll remove the compound you just applied.
Priming & Painting: Prime the patched area and then paint to match the surrounding wall.

Medium Holes (Doorknob Holes, Larger Dents)

These require a bit more work.

Preparation: Clean around the hole. Remove any loose pieces. If the edges are ragged, trim them neatly with a utility knife.
Reinforcement (Optional): For holes slightly larger than a nail hole, you might consider using mesh tape.
Applying Mesh Tape (If Necessary): Cover the hole with mesh%20tape. The tape should extend beyond the edges of the hole.
First Coat of Compound: Apply a thin layer of drywall compound over the mesh tape using a putty knife, embedding the tape in the compound.
Subsequent Coats: Let the first coat dry completely. Apply two or three additional thin coats of compound, feathering the edges of each coat out beyond the previous one. This helps create a seamless transition.
Drying: Allow each coat of compound to dry fully.
Sanding: Sand the patched area smooth with fine-grit sandpaper.
Priming & Painting: Prime and paint to match the surrounding wall.

Large Holes (Larger than a doorknob hole)

These require the most effort and a backer to be installed to patch.

Preparation: Remove any jagged edges and debris. Cut a square or rectangle around the damage for a clean working area.
Measure & Cut: Measure the dimensions of the hole you've created. Cut a piece of drywall to the same size.
Install Backing: This provides support for the new drywall piece. Insert a piece of wood (e.g., a furring strip) larger than the hole behind the existing drywall. Secure it with screws through the existing drywall, above and below the hole. Make sure you have enough purchase on the existing drywall to make the backing secure. These screws serve as anchors for the new drywall patch.
Insert the Patch: Fit the new drywall piece into the hole. Secure it to the wooden backing using drywall screws.
Taping: Cover the seams between the new drywall and the existing wall with drywall%20tape. Apply a thin layer of drywall compound over the tape to embed it.
Mudding: Apply several thin coats of drywall compound over the taped seams, feathering the edges of each coat out beyond the previous one. Allow each coat to dry completely before applying the next.
Sanding: Sand the patched area smooth with fine-grit sandpaper.
Priming & Painting: Prime and paint to match the surrounding wall.

Tips for Success:

Use thin coats: Applying multiple thin coats of compound is better than one thick coat. This helps prevent cracking and ensures a smoother finish.
Feather the edges: Feathering the edges of the compound out beyond the patched area creates a seamless transition and hides the patch.
Be patient: Allow the compound to dry completely between coats. Rushing the drying process can lead to cracking and other problems.
Sand lightly: Sanding too aggressively can remove too much compound and create an uneven surface.
Match the texture: If your wall has a specific texture (e.g., orange peel, knockdown), you'll need to replicate it on the patched area to make it blend in. There are texture sprays and rollers available for this purpose.
Prime before painting: Priming helps the paint adhere better and provides a uniform finish.