(i) Labour has some special characteristics which are not found in other factors of production. 

They are as follows.”

1. Labour is Perishable : If a worker does not work on a particular day, his labour for that day is wasted. Labour is, thus, perishable. Labour cannot be stored. The labourer has to sell his labour immediately irrespective of the prices (i.e., wages) paid to him. It is because of this feature that labour has a weak bargaining power.

2. Labour is an Active Factor of Production : Land and capital are passive factors, but labour is an active factor of production. Without labour, other factors of production, viz., land and capital, cannot produce anything. Labour is a living organism. Hence, it requires sympathetic treatment.

3. Labour cannot be Separated from Labourer : Land and capital can be separated from their.owners but labour cannot be separated from a labourer. Labour and labourer are inseparable from each other. The labourer will have to present himself at a place where work is going on. 

For example, it is not possible for a teacher to teach in the school, while staying away at home. Therefore, the worker and his service go together. He cannot sell his labour like land and capital.

4. Labour is Mobile : Labour alone is a factor which is mobile. It can move from one place to another and also from one occupation to another. Other factors of production such as land lacks mobility.

5. Labour Differs in Efficiency : All labourers are not equally efficient. Some labourers are more efficient due to their ability, training and skill, whereas others are less efficient on account of their illiteracy, ignorance, etc.

(ii) On the basis of skill formation, labour can be grouped into three main categories : 

1. Skilled Labour : Skilled labourers are those who have specialised training for a particular profession and also have long practical experience of the job. These workers are highly paid. Doctors, engineers, lawyers, etc., fall under this category.

2. Semi-Skilled Labour : Semi skilled workers are those who have only a part of a professional training of their trade but have sufficient experience in that line. The semi-skilled workers are paid comparatively less than the skilled workers.

3. Unskilled Labour : Unskilled workers are mainly employed for carrying out such jobs which do not require any specialised professional skill. Labourers who are employed for construction of houses, coolies, etc., are some examples of unskilled workers. They are poorly paid as their number is quite large in less developed countries like India.

(iii) In simple words, efficiency of labour implies the quality and quantity of goods and services which can be produced within a given time period and under certain conditions. According to Dr. Saxena, “By efficiency of labour we mean the amount of work which a labourer can do within a given time.”

Technology has great impact on the efficiency of labour. With the modem and updated technology, the working efficiency of labour is more and the productive capacity increases. The outdated technology adversely affect the overall output (or the productive capacity) ; even though the worker himself may be highly efficient, but due to outdated technology, he will not be in a position to make use of his talent properly.