There are several reasons to research a company or an industry when you are on a job search. You may be interested in the financial stability of a company, the work environment, growth of a company, future of an industry, the people you are being interviewed by, answering some potential "tough" interview questions, salary information, finishing a resume or cover letter, and other reasons that might come up in the process.
Before you even begin to prepare to apply for a position you may want to quickly see if this is a company you want to work for. You can, of course, begin doing this by visiting easily available information at the company's website. This can clearly be highly biased positively for the company. You can also quickly use popular search engines to find more outside and independent information about a company. This might give an incomplete or insufficient view of the company. There are ways to get a better view of what a company or industry is and how they operate.
Using Saint Louis County Library resources and specific publicly freely available websites outlined in this LibGuide should aid in you finding more about about a company on all the stages of the hiring and on-boarding process. You will see some resources repeated under each tab this is because they might be most useful at each stage of the process in this highly iterative process.