What is the advantages and disadvantages of trade union for the employers and employees?

In a very brief and precise reply,

Advantages of trade Unions:

1) Trade Unions are  protecting the interest of it's members. 2) Trade Union are acting in building  good relationship between the employees and employers 3) Trade Unions are acting on raising the technical level of both employees and employers through continues updating and training their working and specialized culture levels.  Disadvantages of Trade Union:1) Trade Unions are usually acting for the benefit of employers in most cases.

2) Trades unions are focusing on the local market not the global markets. 3) Trade Unions are becoming too powerful in some countries and societies and acting against the country's economy in some negotiations with governments.