Animal tissues are classified according to thier structure and function into four major types
1) Epithelial tissues
2) Connective tissues
3) Muscular tissues
4) Nervous tissues

1 Epithelial tissues :-
                    The interior of the body is physically separated from the outside world by skin which forms continuous sheets of cells known as epithelium. Epithelial also line the gut, lungs and urinary tract.
Structurally these cells are flattened and elongated.

2 Connective tissues :-
                     Connective tissues is the major supporting tissue of animal body. It includes skeletal tissues, bones and cartilage. There are two types of connective tissues
A) Soft connective tissues e.g fatty tissues and tendons
B) hard connective tissues e.g cartilage and bones
Blood is also a connective tissue with cells and suspended in fluid medium.

3 Muscular tissues :-
                       Muscle tissues consist of highly specialized contractile cells or fibers held together by connective tissue.
Each muscle fiber is an elongated cell which has the ability to contract and relax. Muscle tissues are furthur divided into three categories i.e skeletal , smooth and cardiac.

a) Skeletal muscle :
                       These are attached to cartilage and bones with the help of thus called stripped or striated muscles. In short skeletal muscles are voluntry which produce power full, rapid contractions and with the help your arms and legs to move.

b) Smooth muscle :
                    These are found around hollow structures such as blood vessel, gut and produce slow sustained contractions. They fatigue but very slowly. These are composed of spindle shaped, un striated muscles. In short smooth muscles are involuntry, unstriated and are under the control of the autonomic nervous system.

c) cardiac muscle :
                    They are only found in heart. These are composed of branched fibers and are capibe of sustained contraction but fatigue. They are also involuntary in action. 

4) Nervous tissues :-

                    It is composed of nerve cells which are called neurons. Neurons are the functional units of nervous system. Each neuron consist of cell body, axon and dendrites. These are capible of transmitting impulses to conduct messages in the whole of the body with the changing enviroment.