Business Transaction: It refers to a sequence of request-response and the related information exchange between the client and the server in order to accomplish a business requirement. For example, an online banking customer transferring money from one account to other is a business transaction.

Test Scenario: It refers to a high critical business transaction or high traffic workflow identified for the performance testing. Normally all the business transactions cannot be tested for its performance. The Paretto analysis helps to identify those specific 20% transactions which is often exercised by the end users rather than testing the remaining 80% non-critical transactions.

Think Time: It refers to the time taken by the user for thinking or clicking on any of the web page links, buttons, etc while navigating through the web site. Think time is a very important parameter which needs to be set while scripting the scenarios using the performance testing tools. The business analysts of the application or web site management team or sometimes even the end user survey might give a realistic picture about the think time requirements of a transaction.

Virtual User: The Performance testing tool simulates the real user traffic by creating virtual users during the performance test. A virtual user is configured in the performance test tool to run the script simulating the real user behavior. Though in real time, users access the application from a unique IP address, more than one virtual user can be configured to access the application from
the same IP address.

Simultaneous User load: The simultaneous users have the active session on the server at any point of time wherein each user will be executing different transactions. For example, if we say 100 simultaneous users load, then there will be 100 active sessions opened up in the server, wherein each user will be performing different set of transactions – one logging in, another
viewing reports, another navigating to the next page, etc. The simultaneous user load of a web site would be always greater than the concurrent user load of a web site.

Concurrent User load: The concurrent users connect to the server and perform the same operation at any point of time. For example, if we say 100 concurrent user load, all 100 users would be logging in at the same point of time, view the reports at the same point of time, etc. For example, an online banking web site might have 10,000 – 20,000 simultaneous user load, but
1000 to 1500 concurrent user load.

Performance Requirements/Goals: It refers to the quantitative way of putting forth the criteria for claiming the system performance is good. The performance requirements of an application are often expressed in response time, hits per second, transactions per second, etc. The performance requirements of the System Under Test (SUT) need to be quantitatively expressed in the performance test plan.

Workload: It refers to the user load subjected by a web application under real time user access or during the performance test and the way the users are distributed between various transaction flows. Normally, the web server log files of a web site can be analyzed to learn about the workload of the site (if the web site is already in production). For web sites which are yet to go
alive for the first time, a workload model needs to be developed based on the discussion with business analysts, application experts, etc. It is very important to know the workload of the application before conducting the performance test. Conducting the performance test for a system without proper analysis on the workload might lead to misleading results.

User Abandonment: It refers to the situation wherein the end users exit from the web site because of the slow performance of the site. The user abandonment rate varies from web site to web site. A low priority web site might experience a high user abandonment rate compared to the payroll web site. Analysis on the abandonment rate of the site needs to be done before
concluding on the load on the site.

Baseline Test: It refers to the test conducted to measure the application performance for 1 virtual user load. The baseline test is often conducted to collect the metrics about the system performance for 1 user load and thereby it could be used for comparing the system performance at a high load condition. It also helps to check the validity of the test script.

Benchmark Test: It refers to the test conducted to measure the application performance for a low load condition. Normally for a benchmark test, 15 -20% of the target load can be considered. The objective of the benchmark test is to validate the correctness of the test scripts and to check the readiness of the system before subjecting it to a high load. It helps to know whether various
components of the system collaborate as per the design and meet the performance test SLA for 20% of target load.
Hit: It refers to the server request for accessing a web page or a file or an image from a web server. For example, if a web page contains 5 images, then a user visit to that page creates 6 hits on the web server (5 hits for fetching each of the images and 1 hit for fetching the web page).