The U.S. Securities and Exchange Commission gives a unique number to each company that files forms electronically. That number is called a Central Index Key or "CIK" number. You can use the CIK number to pull up SEC filings for a company in the SEC's free Company Search, and in the commercial databases such as Morningstar Document Research, Livedgar and Bloomberg.
Conversely, you can look up a company's CIK number by name using the SEC's free CIK Lookup or equivalents on Livedgar, Bloomberg, etc.