Main Industry identifies the borrower’s dominant business sector when multiple activities exist. In MSME underwriting, a borrower may manufacture one product, trade another, and provide related services, but the lender needs to know which activity drives most revenue and risk. For example, a firm registered for general trading may actually earn most income from construction material supply. Main industry affects margin benchmarks, working-capital cycle, seasonality, policy restrictions, and sector outlook. This field matters because wrong industry tagging can lead to wrong comparisons and risk treatment. The common caution is to classify based on actual sales contribution and business model, supported by GST data, invoices, financial statements, and borrower discussion.