A price band is the range, with a lower limit (floor) and an upper limit (cap), within which investors may bid for shares in a book-built IPO. The company and its lead managers announce the band in the price band advertisement, usually a few working days before the issue opens, and the Red Herring Prospectus carries the same range. The final issue price is discovered through bidding and is fixed inside this range, so it can never be higher than the cap or lower than the floor. Under SEBI rules the cap should not exceed 120 percent of the floor price, which keeps the range reasonably tight. Retail investors normally bid at the cap or at the cut-off price so that their bid stays valid whatever the final price turns out to be. The band matters because it sets the maximum money you must keep blocked in your bank account: lot size multiplied by the cap price. Companies can revise the band during the issue, but that requires public notice and an extension of the bidding period by at least three working days. Fixed-price issues do not have a band; they have a single price.
Example: Suppose a company announces a price band of Rs 95 to Rs 100 and a lot size of 150 shares. One lot at the cap costs Rs 15,000 (150 x Rs 100). If book-building ends with the price fixed at Rs 98, you are allotted shares at Rs 98 and the extra blocked money is released after allotment.