Caslte breaking tactics

So your opponent has just caslted and it seems invincible. Well test if it's invincible or not. To break the caslte, you have to know the weakness of the castle. Usually, the weaknesses are 1.King has to move under check. 2. Knight can easily fork king, rook and queen. 3. If rook or queen is aiming the king, the pawn can't move diagonally. 4. If the king has no where to move, king is stuck. 5. The rook  can't help the far edge. 6. Use your pawns to break castle.

White's turn for all these diagrams

For the top picture..... It seems like the best move for white is queen stepping into the center postition and bishop eating black knight. But can you get more creative? maybe use knights? combos? right order of moving pieces?

For the above picture....... Black's king is well protected but seems vulnerable in h file after some obstacles are removed. Can you see the steps? Remember! Get rid of heavy obstacles first!

Lesson after all these exercises..... The ultimate piece to checkmate might be queen or rook. Knight and queen combo or bishop and queen combo is dangerous to king's weak side. Knights and pawns can be sacrificed in order to remove obstacles or open a line.