The definition of ISO:

ISO is the abbreviation for International Organization for Standardization, in other words, it is a quality management standard constituted by the international standardization organization. ISO9000 Certificate is the guarantee that the products and the services of the relevant institute are provided as a result of a management concept that is administered and directed in compliance with a management system recognized internationally and as a result it is a guarantee for the sustainability of the product and service quality of the mentioned institute.
ISO9001 is a standard that defines an efficient quality management system. When the institute satisfies the requirements of this standard, it may be granted ISO9001 certificate. The certificate proves that the products and services of the institute are produced in compliance with a standard that is recognized internationally. The standards center is developed by International Organization of Standardization, IOS, located in Geneva, Switzerland, which has more than 90 member countries.  The authority to authorize the certification companies is given to the accreditation boards of the member countries. The accreditation authority in Turkey is given to TÜRKAK.
Different standards developed for similar technologies in different countries or regions are used as “technical barriers for trade” from time to time. The most important function of ISO today is to prepare the standards that are recognized internationally such as ISO9000 quality management standards and the other product standards and to eliminate such barriers blocking the trade.
What is ISO9000? : It is the whole system of standards published by ISO that guides the establishment and development of a quality management system by the organizations for increasing the customer satisfaction.
What is ISO9001? : It is the standard defining the conditions that should be applied during the establishment of Quality Management Systems, which is subject to certification inspection. It is the name of the certificate given.
What is ISO9001:2001? : ISO9000 standard is reviewed by ISO every 5 years and the required revisions within the direction of the opinions of the implementers and the requirements are performed and re-published. The figure 2000 is the version date indicating that this revision is prepared and published in 2000 (ISO9001:2000 version).
The Benefits of ISO9001  
The Use of ISO9001 Certificate: ISO9001 certificate is requested by many customers. This certificate itself shall provide market advantage for you. However this benefit, as mentioned before, is a short-term one. ISO9001, besides market advantage, provides your institute with a continuous improvement mechanism and discipline. Yet, receiving this certificate shall not mean that you had achieved perfection. In an institute with ISO9001 certificate, each problem is perceived as an opportunity for improvement. Preventing the repetition of the problem is more important than solving it. The results of a research applied to 720 certified companies in our country underline the benefits of ISO9001 as follows:
External benefits:
    Strengthening the image of the institute,
    Customer satisfaction,
    Increasing the number of customers,
    Increasing the competitive power,
    Better supplier relations.
Internal benefits:
    Efficiency of the management,
    Positive cultural change,
    Formation of the awareness of quality,
    Better documentation,
    Standardization and stability,
    Increasing the efficiency and productivity,
    Decreasing the costs.

The History of ISO9001:2000

    In 1963, MIL/Q/9858 (In defense technology in the USA)
    In 1968, AQAP standards (In NATO member countries) 
    In 1979, BS 5750 (In England)
    In 1987, ISO9000 series (by ISO)
    In 1988, EN 29000 standards (by CEN)
    In 1988, TS 6000 was published as Quality Assurance System     standard
    In 1991, TS-EN-ISO 9000
    In 1994, it was revised by ISO (9001:1994/9002:1994/9003:1994)
    In 1996, EN 29000 series were published as EN-ISO 9000.
    In 2000, it was revised by ISO and was published as 9001:2000.

  The standard was first published in 1987 as Quality Assurance System standard. At this stage, the standard was composed of 3 sub-standards: ISO9001, ISO9002, ISO9003. The institutes were applying one of these 3 standards within the direction of the scope of their activities and were going through inspections. This version of the standard was mainly focused on the issues of correct production and troubleshooting. The standard was first revised in 1994 and was re-published as Quality Assurance System standard. At this stage, the standard was again composed of 3 sub-standards: ISO9001, ISO9002, ISO9003. The institutes were applying one of these 3 standards within the direction of the scope of their activities and were going through inspections. This version of the standard, in addition to the issues of the previous versions, was also focused on the issue of error prevention. The standard was finally revised in 2000 and this time it was published as Quality Management System standard. There is only ISO9001:2000 standard available as the basis for the certification. ISO9002, ISO9003 are the standards which are not up to date anymore. However the guide standards such as ISO9000, ISO9004, ISO19011 that support the main standard ISO9001:2000 are also published. The institutes, independent of their scopes of activity, apply only ISO9001 standard and take this certificate.  However, the activities that are subject to certification and the excluded articles of the standard are identified on the certificate to be taken. This version of the standard presents a process-based management model which targets increasing the continuous improvement and productivity in addition to the issues of the previous versions and which emphasizes focusing on customers
ISO 9001:2000 Quality Management Principles
1. Focusing on Customers: The institutes depend on their customers and due to this they should understand the current and future needs of their customers, they should comply with the conditions of the customers and should try to go beyond the expectations of the customers
2. Leadership: Leaders organize, determine the unity of direction and purpose. Such an environment should be established and sustained in the leader company so that the people can participate in full in achieving the targets of the institute. 
3. The participation of the employees: The employees at all the levels are the values of the institute and their capabilities may be used for the benefit of the institute upon their full participation.
4. Process Approach: Successful results can be achieved more efficiently when the activities and relevant resources are managed as a process.

P  Plan .. Determine the Targets & Processes
A  Apply.. Apply the Processes
C  Control.. Monitor & Measure
I   Improve.. Provide Continuous Improvement

5. System Approach to the Management: Determination, understanding and management of the processes that are related to each other as a System provide the efficiency of the institutes and enable the productivity in realization of the targets.

6. Continuous Improvement: Continuous improvement of the whole performance of the institute should be the permanent target of the institute.

Improvement: it means increasing the characteristics and features of the product and/or increasing the efficiency and productivity of the processes used in order to produce and distribute these.

7. Realistic Approach in Decision Making: Efficient decisions are based on the analysis of the data and information.

8. Supplier Relations Based on Mutual Benefit: An institute and its supplier are dependent on each other and they have mutual benefits in increasing their capabilities with regards to formation of a value.