An industry is a group of companies that are related based on their primary business activities.
(North American Industry Classification System) and SIC (Standard Industry Classification) codes are an easy way to group companies engaged in the same economic activities.
SIC was used by the US and Canadian governments until 1987, when both countries adopted NAICS. Some commercial databases continue to use SIC, however.
You can search NAICS here and SIC here (or use Google).
Industry Reports discuss the "big picture" of an industry- trends, products or services, market share, major companies, and other factors. You will likely have to look at more than one source to get the complete picture. Market reports are often not free, as time and money goes into collecting information about industries, but there are other free ways to get industry information. FYI- If an industry is very new, niche, or tech-based, there may not be enough information gathered for a full report, so you may need to get your information from other sources such as articles, blogs or websites.
Research your industry, identify companies and trends with these resources...
Part of researching your industry is also understanding your competitors. Here are some freely available resources that you may want to use for this:
Industry associations and trade groups are an excellent free source of industry statistics and reports, generally available on their websites or through their publications- an internet search using your preferred search engine is generally the fastest way to find key associations in your desired industry. Use a variety of search terms along with your key words (eg: poultry, beer, etc) like association/group", "trade group," "trade organization," etc.