Tissue is defined as a group of similar cells of same origin that together carry out a specific function.
Cells of different tissues are differentiated to carry out specific activities. This means that a particular function is carried out by a cluster of cells or tissue at a definite place in the body. In this way, tissues show the division of labour in an organism.
Examples: In human beings, muscle cells contract and relax to cause movement. Nerve cells carry messages. Blood flows to transport oxygen, food, hormones, waste materials and so on. In plants, vascular tissues conduct food and water from one part of the plant to other parts.