Trade unions are organizations of workers, which are formed in order to improve their working conditions. The early analysis and definition of trade union is provided by Webb who presents an interesting description about the origins of trade unions in Britain. According to Webb, a trade union is defined "continuous association of wage-earners for the purpose of maintaining or improving the conditions of their working live"(Webb, 1920). However, trade unions today have evolved into more complex organisations with various kinds of structures and purposes, and they also have important political and social objectives in parallel with economic objectives.

The subject of this essay is an exploration and explanation of these complexities with regard to various labour market factors. We first discuss the theoretical perspectives of trade unionism starting from its origins in Webbs' analysis. From this point we continue with a discussion of the impact of the two primary and extreme approaches to trade unionism known as revolutionary unionism and business unionism. In this part we also discuss unitarist and pluralist perspectives of trade unionism. Furthermore, we investigate the changing nature of the labour market arising from elements within the labour force and the effects of labour market factors on union practices. We also evaluate labour market issues as they affect trade union growth and decline.
In the second part, we present descriptions of trade union structure associated with the models of Turner, including union mergers shaped by new policies and practices. The third part is a consideration of varieties of trade union government and union democracy. The aim is to highlight the internal organisational structures committed to the about the fulfillment of worker demands.
The last part concludes by by discussing explanations for the varieties of trade unions types.

Throughout the evolving process of industrialisation (19th century), trade unions developed as a response to capitalism. Under the capitalist economic system, the owner/manager of capital and labour is interested in paying the lowest possible wage, while the worker who sells his/her labour is interested in the highest level of wage. This resulting conflict between employer and employee stimulated the trade union movement as a means of finding solutions for these problems (McIlroy, 1995).
The principal purpose of trade unions is to protect the workers through the collective bargaining process. As this term was first introduced by Webb, he describes this process as one of the methods utilized by trade unions through which organized groups of workers negotiate with their employers concerning the conditions of employment. According to Webb, collective bargaining enables the workers to secure their greater advantage in their working conditions through unionization. The effects of trade union action through collective bargaining have been shown to have great impact on industrial behaviour (Webbs, 1920). Therefore, trade unionism is cited as an important element of the work force.

Throughout the development of trade unionism, different schools of thought have emerged. One of these, described as the revolutionary type of unionism is the class-based view which focuses on the continuous struggle between workers and capitalists. Its aim is to reorganize and control industrial relations (Hyman 1975).

Another understanding of unionism founded on the belief that workers and capitalists have common interests and that both side could be satisfied through the negotiation process of collective bargaining. The ultimate goal of business type of unionism is a fair wage for the worker in the realization of the highest levels of production. This type of union developed in the United States and its theoretical bases were outlined by Perlman (Perlman, 1928).

Beyond merely considering industrial conditions for their members, many of the European and British unions include political objectives. As a result, trade unions are linked to political parties and hold strong influence over many political policies. In contrast, American unions are restricted to industrial and economic objectives and they have no links to political parties. In this sense, there is a great distinction between unions in US and in Britain.

Other theoretical considerations about trade unionism are presented by the unitarist and pluralist perspectives. Unitarists argue that the interests of the employer and employee are one and the same and that both sides benefit from their relation of exchange in the constitution of business. According to unitarist concept, trade unions are dysfunctional, illegitimate and present a threat to the harmony of the relationship between employer and employee. The Pluralist approach states that there are different interest groups within the work organisation. Therefore, workers have the right to express their own needs and to improve their working conditions through collective bargaining process. In this point, trade union is a pluralist concept which encourages and defends its legitimacy (Rose, 2001, p. 308)
The developments outlined above help to explain various features of trade unions in terms of their political influences.

The conditions of the labour market affect the position and power of trade unions. In British context, during the post-war period (after 1945), the gender composition of labour force shifted considerably. The numbers of working women have increased while the number of men fairly stable. The most significant change came about through the decline of manufacturing and particularly within 'traditional' industries. During the 1960s and 1970s there was considerable growth in the service sector, especially health and education (Nolan and Walsh, 1995).

Subsequently, there has also been a shift from full-time employment to part-time employment, mostly represented by women. As a result of government policies and privatizations, during 1980s in Britain, employment opportunities have generally declined, elevating the rate of unemployment. Trade unions experienced membership losses. The growth in employment in newer sectors of British industry has been accompanied by new style of collective bargaining and industrial relations. In particular, after 1979 Thatcher government introduced a new policy to the labour market which has greatly reduced the ability of trade unions to protect members' jobs and work conditions (Nolan and Walsh, 1995). It enhanced the power of employer, and enabled them to reduce the rate of wage and to control working conditions (Farnham and Pimlott, 1995).

More generally, changes in employment practices provided a shift in employer strategy, encompassing the redefinition of remuneration, promotion and work allocation structures with regard to internal labour markets. As a result of this, organisations have faced two kinds of trade union action: union avoidance and union abundance. Union avoidance became the tendency in the U.S., while in Britain the policy changes in the labour market stimulated increased unionizing activities as employees sought to protect their working conditions (Nolan and Walsh 1995).

Changes in the nature of the labour market play a significant role in the fluctuations related to trade union membership and density. Waddington and Whitson provide a detailed overview of trade union membership. In Britain, after 1979, the overall picture is characterized by a decline in union membership and density. While there was an increase in the unionization of women and white-collar workers, the same activities of men and manual workers saw a decrease (Waddington and Whitson 1995).

There are many generally acknowledged factors which serve to explain membership decline. Union membership and density are determined by a combination of factors: attitude and actions of employers, government policy, composition of work and of the workplace. According to Waddington and Whitson (1995), the decline can be understood in terms of 'business cycle explanations' which tend to view fluctions in trade union membership in parallel with changes in market prices, wages and unemployment. Increases in real wages may reduce incentives for employees to join trade union. This is the case with white-collar workers whose membership increased during the 1970s. As a result of enhanced real earnings of white-collar sector, the union membership declined during the 1980s. Business cycle explanations also identify high levels of unemployment as causes for membership decline, since this factor enables employers to resist unionisation of workers (Bain and Elsheikh, 1978)

Derecognition of trade unions by employers to exclude trade unions from control of the employment relationship is another explanation of trade union membership decline. In general, employment policies during the 1970s included the recognition of the important role of unions in mediating their relations with the work force (Gallie, 1997, p. 19). Nevertheless, the failure of some unions to secure the recognition of employers was another factor contributed to membership decline particularly between 1983 and 1990. Another factor in the decline of union membership was the increase of employment of women, white-collar workers and part-time workers, which in comparison with other worker groups have generally lower rates of unionisation.

Trade unions are dynamic organisations with a wide variety of sizes, shapes and types and they are constantly changing in response to their social, economic, technical and political environment. As Coates and Topham (1988) pointed out the classification of trade unions is no longer simple matter (p. 41). One of the factors which characterizes and distinguishes the various types of trade union structures is the recruitment pattern based on the skills profile required for union membership. Considering union structure in terms of recruitment, Turner's (1962) model is the most useful classification, ranging from open to close union types. An open union is interested in providing numerical strength to reinforce its bargaining power while a closed union aims to control the supply of labour and restricts entry to the union. Craft unions whose membership is restricted to a particular category of skilled workers constitute closed unions. General unions whose membership has no restrictions on potential membership are classified as open union types. On the other hand, these categories of trade unions are not fixed: closed unions may become open as industries develop (Turner, 1962).

Two other kinds of strucure are the vertical and horizontal union types. Horizontal union recruit members from one of several grades of workers. Craft unions fall into this category of union. In contrast, the aim of a vertical union is to recruit all workers with a common industrial background whatever their grade. Therefore, vertical unionism corresponds to industrial union types.

Associated with structure, trade union mergers have been flourishing, especially during the last decade. The main reason of union merger is to offset the loss of financial reserves and other resources which results from dwindling union membership (Undy et al, 1981). According to Undy et al., union mergers are seen as a way of compensating for the disappearance and/or decline of unionisation within the competitive industrial arena.

Although the above approaches to union types are useful in delineating the various forms and their differences, it must be pointed out that these tendencies are limited to the complexities of organisation within the context of British trade unionism.

The internal structure of each trade union plays a significant role in differentiating one from the other. In order to understand the internal organisation of a trade union, we shall look at membership participation and democratic process within the unions constitute union government. According to a number of researches, trade unions have tendency to be organized according to 'representative democracy' type of government. Michels (1959) asserted that as in other organisations, trade unions operate according to an 'iron law of oligarchy'. This means that, within the trade unions a small group of bureaucrats developed who used their control over resources and imposed their own goals on the members. Turner's study (1962) supports the Michels model which asserts that trade unions are oligarchic in their nature. In Turner's model of union government, the 'exclusive democracy' type refers to those organisations whose membership is homogeneous and characterized by high membership participation. Craft unions are typical examples of this union government type.

The second type is the 'aristocracy' model whose membership is more heterogeneous and sectionalized. In this type, one group or section has higher participation than the other groups and consequently dominates the union. Yet another type is 'popular bossdom' which is characterized by extremely heterogeneous membership and very low rate of membership participation. Open unions are an example of this type of union (Turner 1962).

The internal democracy of trade unions is crucially important in making unions stronger and better able to protect for the rights and interests of their members. Union democracy can be provided by three important elements: member participations, the active role of shop stewards, and the existence of opposition inside the union which is seen as a vital aspect of the democratic process (Hughes, 1968). In many instances the active participation of trade union members and the advancement of their democratic rights influence their behaviour in the decision-making process in the control of their working conditions in the enterprise. As a concept, union democracy constitutes representation of the members and the protection of their interests. Either members represent themselves directly or employee representatives makes decisions on behalf of their constituents. Different types of union government and systems of election of representatives affect the level of employee participation within the union.

The shop stewards are the trade union representatives in the workplace, elected by the workers to protect their interests in all dealings with the employers. Shop stewards are responsible for negotiations with management in grievance and dispute procedures, as well as in the collective bargaining process on behalf of members. Since they constitute the central focus of worker representation, shop stewards maintain one of the most effective ways of safeguarding democratic process within trade unions.

Union democracy can be effected by the existence of opposition inside the unions, providing the opportunity for extensive participation and free speech by the members. The central aim of trade unions is to protect the working conditions of their members and it is important to look at the union system of government and structural factors which emphasis how the trade union supports their members.

The structure, purpose and functions of trade unions are evolved and differentiated through the process of labour market change, as industrial society develops. Such an evolution process is also altered by political, historical, economical and social factors. As we have stated, these factors lead to the development of trade unions with a much wider range of aims and functions. Moreover, change in technology and composition of workforce stimulate the development of new forms of trade unionism. However, trade unions still retain their essential nature as the representative agency of the employees within the organisation, with primary role to protect the workers through collective bargaining with the employers and also to lobby the government in public policy making in the labour and employment fields.

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