Overview
Form S-1 is a the most basic form filed to register securities, for which no other form is authorized. This form is most typically seen filed in initial public offerings (IPOs).

Form Uses
This form is used to gain financial and other material information about a company that is issuing securities. The most common use for this form is in initial public offerings, where it can offer insight into a company's valuation and business operations.

Reading the Form
There are three major portions of the S-1 form:

1. Letter to Shareholders from Parent Company - This can give you a nice history of the parent company, their reason for the spin-off, and and other relevent information.
2. Information Statement - This section contains all the information investors need to know. Occasionally, portions of this section will be left blank and amended (with S-1/A filings) at a later time.
3. Financial Information - This section contains all the financial information, including pro-forma statements. These statements show what the financials would look like if the spun-off division were its own company in the past.