Performance Testing (PT):
   Testing the stability & Response Time of an application by applying Load is k.a., PT.

   The performance testing will be done for web applications only.

Stability: Ability to withstand for which it is designed for is k.a., stability.
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Response Time: A total time taken to receive the link or page is k.a., Response Time.

RT = T1 + T2 + T3

But T1 & T3 are influenced by many factors. Such as:
1. Network speed
2. Network Traffic
3. Service Provider
4. Hardware capacity of the computer.
  
Hence we need to standardize the T1 & T3 before performing PT. While publishing the PT results also we should say under the specific speed of internet & specific Hardware capacity the application response time is 2 sec.
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Load: Number of users working on the Software.
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Types of PT: 
1. Load Testing
2. Stress OR Torture Testing
3. Volume Testing
4. Soak Testing

1. Load Testing: Testing the stability and Response Time of an application by applying load which is equal OR less than the designed number of users is k.a., Load Testing.
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2. Stress OR Tortute Testing: Testing the stability & Response Time of an application by applying the load which is more than the designed number of users is k.a., Stress/Torture Testing.
    This type of testing is usually done to find the scalability limit for the s/w.

It can be done in 2 ways:
1) Restrict the load & reduce the hardware capacity
2) Restrict the hardware & increase the load.

Note: The stress testing must be followed by Load testing.
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3. Volume Testing: Testing the stability & response time of an application by transforming huge volume of data through it is k.a., Volume Testing.
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4. Soak Testing: Testing the stability & Response Time of an application by applying the designed number of load contineously over a period of time is k.a, Soak Testing.
   It is required to simulate the real time scenario where the contineous load will be present on the servers.
  To do that we contoneously apply the load to the server over a period of time
  Ex: 72, 92 OR 120 hours.
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Note:
1. Not all the application requires PT. We do PT on those s/w which provides ROI (Return On Investment)
2. Not all the pages requires PT. We do PT on those pages which are frequently accessed by the end users.

3. Based on Architecture the web applications are devided into 2 types
  (a) Client Server Architecture
  (b) Web Application
Both requires PT if there is a ROI.

4. Based on the client resource consumption the applications are devided into 2 types
  (a) Thin client: The application which uses less client resource & whole process takes place at server side.
  Ex: Gmail, FB etc

  (b) Thick client: The application which utilizes more client resources and as well as server resources.
  Ex: Yahoo messanger, Skype

Both requires PT if there is a ROI.
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Tools used for PT are:
Load Runnner: Vendor is hp.
Jmeter
SoapUI
ReadyAPI