What is plasmolysis ? Mention the types of plasmolysis

Shrinkage of the protoplast of a cell from its cell wall under the influence of a hypertonic solution is called plasmolysis. There are two types of plasmolysis:
(a) Incipient plasmolysis - Due to continuous exosmosis the protoplasm withdraws itself from the comers.
(b) Evident plasmolysis - Protoplast withdraws from
the wall except one or few points due to excessive exosmosis.