Quoted from the website below:

	"This paper describes httperf, a tool for measuring web server 
performance. It provides a flexible facility for generating various 
HTTP workloads and for measuring server performance. The focus of httperf 
is not on implementing one particular benchmark but on providing a robust, 
high-performance tool that facilitates the construction of both micro- 
and macro-level benchmarks. The three distinguishing characteristics of 
httperf are its robustness, which includes the ability to generate and 
sustain server overload, support for the HTTP/1.1 protocol, and its 
extensibility to new workload generators and performance measurements. 
In addition to reporting on the design and implementation of httperf this 
paper also discusses some of the experiences and insights gained while 
realizing this tool." 

"This paper" refers to the paper that was written on this program. I don't
think I could possibly summarize it better than the above paragraph.

WWW: http://www.hpl.hp.com/research/linux/httperf/