What is the general procedure for passaging adherent cells?

The general procedure for passaging adherent cells is described in the steps below. 

1. Remove the old culture media and rinse cells with a balanced salt solution.
2. Detach the cells from the bottom of the flask by using EDTA pre warmed  to 37°C, or spraying with balanced salt solution (BSS) and tapping the plate, or through proteolytic enzymes such as Trypsin at concentration 0.025%-0.5%
3. Prevent clumping of the cells by placing them in a single-cell suspension.  Then, inactivate the cells after harvesting them in a large volume of growth media or BSS+FBS (fetal bovine serum) and centrifuge the cells.
4. After detaching the cells, suspend them in a small amount of growth medium and perform a cell count using a hemocytometer. Adjust the cell concentration by diluting them to the target density. Then, distribute the cells into new dishes by adding enough medium to allow pipetting 1-2 ml into each dish. Gently swirl the dishes to evenly spread the cells through it. Lastly, seed a known amount of cell suspension into a new culture and carry out microscopic visualization.