What are the types of staining techniques?

The two types of staining techniques are simple staining and differential staining. 

Simple staining only uses one type of stain. This staining technique is used to provide significant contrast between the microbial cell and its environment to study a cell's morphology. It also allows for the observation of the shape, size, and arrangement of bacterial cells. 

Differential staining involves the use of 2 or more contrasting stains. Differential staining can be broken down into 2 categories: separation into groups (for gram staining and acid-fast staining) and the visualization of structures (from flagella stain, capsule stain, and spore staining). This staining technique allows us to differentiate between distinct species of bacteria.