Cell wall is present in plant cells and is absent in animal cells. Cell wall provides rigid structure to the plants which help the plants to sustain in harsh environmental conditions because plants are immobile. Whereas animal cells have cell membranes which provide flexibility to animal cells to facilitate movement in animal cells and to differentiate further to form various cells, tissues, and organs.

Introduction:
The cell wall is a rigid, protective layer that surrounds the cells of plants and some other organisms. It provides mechanical support to the cell and helps to maintain its shape. However, animal cells do not have a cell wall. This is because of the following reasons:

Difference between Plant and Animal Cells:
Plant cells and animal cells have some similarities and differences. Some differences between plant and animal cells are as follows:

The Cell Wall:
The cell wall is a rigid, protective layer that surrounds the cells of plants and some other organisms. It is made up of cellulose, which is a complex carbohydrate. The cell wall provides mechanical support to the cell and helps to maintain its shape. However, animal cells do not have a cell wall.

Functions of the Cell Wall:
The cell wall performs the following functions in plant cells:

1. It provides mechanical support to the cell.
2. It helps to maintain the shape of the cell.
3. It prevents the cell from bursting when it absorbs water.
4. It protects the cell from mechanical damage.

Why Animal Cells do not have a Cell Wall:
Animal cells do not have a cell wall because of the following reasons:

1. Animal cells do not need the mechanical support provided by the cell wall because they have a cytoskeleton, which provides structural support to the cell.
2. Animal cells need to be able to move and change shape, which would not be possible if they had a rigid cell wall.
3. Animal cells are able to regulate their water content more effectively than plant cells, so they do not need the protection from bursting provided by the cell wall.

Conclusion:
In summary, the cell wall is present in plant cells and not in animal cells because plant cells require the mechanical support and protection provided by the cell wall, whereas animal cells do not. The absence of a cell wall in animal cells allows them to move and change shape more easily, which is important for their function.