Essential questions to ask from the start:
In addition to the company or organization's size, the answers to these questions will affect the amount and type of information that is available about it.
In the U.S., companies with shares that are publicly traded on the stock exchange are required by law, per the U.S. Securities and Exchange Commission (SEC), to file detailed financial and other information. These companies have one to five-letter ticker symbols that can sometimes be used in place of the company's name while searching library databases and the Internet.
Even with federal disclosure obligations, it can be difficult to find information on subsidiaries of larger parent companies, since public companies do not have to report on them separately; and private companies, large and small, are always a little tricky because they do not have to disclose.
Nonprofits are exempt under section 501(c)(3) of the U.S. Internal Revenue Code, but because of this status, these organizations are required to file certain financial and operational information annually.
For free but limited company snapshots that may help answer the above questions and more, try searching the Dun & Bradstreet Business Directory.
Google Advanced Search can reveal all kinds of useful data and information including company "org charts." Try entering the company name and organizational chart. The filetype filter is also great for uncovering PDFs, Microsoft (i.e., Excel, PowerPoint, and Word) files, and more. You can even use the site filter for company websites without a prominent search feature.
A few key documents to seek out:
In addition to Investopedia's Financial Terms Dictionary, these terms and thousands more can be found in Campbell R. Harvey's Hypertextual Finance Glossary, which may come in handy when reading through annual reports and SEC filings. (Do not be put off by the design of the latter resource!)
Financial information for private and subsidiary companies is not as readily available as that of publicly traded and parent companies, though some data can be found in the PrivCo database.
Other, anecdotal evidence of financial status is often shared in local newspapers, magazines, newsletters, and trade journals, and sometimes, actual numbers are provided (however approximate or vague they may be). These snippets can be found via article, or "literature," searches in library databases.
Google (or another search engine) can help fill in the gaps. When searching company websites look for pages with titles like "About Us" or "For Investors." Social media (e.g., Facebook, Twitter, LinkedIn, YouTube, Instagram, and even TikTok) can be especially helpful for small, private companies.