For an equity offering the prospectus is the core of the form-s-1. For a fund it is a standing document updated annually, with a statement of additional information behind it and, for many funds, a short summary prospectus delivered instead.
What matters most is usually near the front and the back: the fee table, the strategy description, the risk factors and, for structured or leveraged products, the worked examples showing how payouts behave in unfavourable paths.
A preliminary or red herring prospectus circulates before pricing and lacks the final price and share count. Delivery obligations are now satisfied electronically for most offerings via sec-edgar, so nobody posts you a booklet any more.
Related: form-s-1, securities-act-1933, sec-edgar, etf, jobs-act