There are many online sites you can use to develop a targeted list of potential employers and to dig deeper for employment information.   The most obvious place to start in researching a particular company is its own web site.  When looking to increase your knowledge of a particular market segment, geographic area or industry you should use broader tools.  Sites that provide competitive analysis, reports and even employee-reported data can all be useful.   

The biggest challenge in using the internet for research is avoiding the inevitable distractions that arise from access to too much unrelated information as well as figuring out which resources contain useful and valid content.   The chart linked here includes recommended online resources serves as a starting point.  While some of the resources listed also provide job postings, our intent is to list those sites most useful for pure research.