Starting middlegame

The middlegame starts when development is done and the trading process has begun (at least that’s how many players see it).  Assuming both players have an equal footing during the opening moves, the middle gameplay is all about trading pieces to gain positional advantage.  The middlegame can be short and be done with one trading sequence, or drag out the entire game. This part of the game may be the hardest to see the next best move since the board is covered with pieces and in order to plan ahead, you would have to take into account each piece.  Moving a certain piece may open opportunities for other pieces to move so it may be more likely for people to make mistakes because they have a hard time keeping track of every piece.