Difference between various software testing terms

Here are some similar sounding terms that confuse most people. We need to get more clarity on what the difference between these terms is, so here is an attempt to do that. The Difference Between Quality Assurance, Quality Control, And Testing, explained below.
A large number of people are confused about the difference between quality assurance (QA), quality control (QC), and testing. These terms are closely related, but they are essentially different concepts and we need to understand the difference between them. Their being difference does not minimize the importance of all of them, and since all three are critical to managing the risks of developing and maintaining software, it is important for software managers to understand the differences. The definition of these terms is below:
• Quality Assurance: Defined as a set of activities designed to ensure that the development and/or maintenance process is adequate to ensure a system will meet its objectives.
• Quality Control: Defined as a set of activities designed to evaluate a developed work product.
• Testing: The process of executing a system with the intent of finding defects, including all the necessary planning for the testing, and just does not mean the actual execution of test cases.
QA activities ensure that the process is defined and appropriate. Methodology and standards development are examples of QA activities. A QA review would focus on the process elements of a project - such as whether the requirements are being defined at the proper level of detail. In contrast, QC activities focus on finding defects in specific deliverables - e.g., are the defined requirements the right requirements. Testing is one example of a QC activity, but there are others such as inspections. Both QA and QC activities are generally required for successful software development.
There can be disagreements over who should be responsible for QA and QC activities -- i.e., whether a group external to the project management structure should have responsibility for either QA or QC. The correct answer will vary depending on the situation, but here are some suggestions:
• While line management can and should have the primary responsibility for implementing the appropriate QA, QC and testing activities on a project, an external QA function can provide valuable expertise and perspective, and his help is in most cases, beneficial.
• There is no right value for the the amount of external QA/QC, more like it should be a function of the project risk and the process maturity of an organization. As organizations mature, management and staff will implement the proper QA and QC approaches as a matter of habit and as a result, the need for external guidance reduces, with review being more relevant.