A company's total market value (share price × shares outstanding), used to bucket stocks into large-, mid-, and small-cap.
Market cap is simply current share price multiplied by the total number of outstanding shares. SEBI's official classification ranks all listed companies by market cap and buckets them: the top 100 are large-cap, the next 150 are mid-cap, and everything ranked below 250 is small-cap.
Large-caps are generally more liquid and stable; mid- and small-caps carry higher growth potential alongside higher volatility and liquidity risk — they can be harder to buy or sell in size without moving the price.