An industry is a group of competitors who manufacture, produce, and/or sell the same or similar products. Industries can be very narrowly or broadly defined based on who is included as a competitor.
The U.S. government defines industries by NAICS (North American Industrical Classification System) codes. An industry being defined at a 2-digit NAICS code level is defined at a broad level. An industry defined at a 6-digit NAICS code level is very narrowly defined.
The more specifically an industry is defined, the more challenging the research will be.