Performance Testing
Performance testing is the one which measures response times and transaction rates. It is the process of exercising an application by emulating actual users putting a load on your system for the purpose of finding system bottlenecks. In general, we want to measure the Response Time, Throughput, and Utilization of the Web site while simulating attempts by virtual users to simultaneously access the site. One of the main objectives of performance testing is to maintain a Web site with low response time, high throughput, and low utilization.
Response Time is the delay experienced when a request is made to the server and the server's response to the client is received. It is usually measured in units of time, such as seconds or milliseconds.
Throughput refers to the number of client requests processed within a certain unit of time. Typically, the unit of measurement is requests per second or pages per second. [Source]
Also See:
Load Testing Tools
Stress Testing Examples
Difference between Load & Stress Testing
Excellent Performance Testing Articles
What is Load Testing
What is Stress Testing