290 PC is the section of California Penal Code that defines Sex Offender Registration requirements
California Department of Justice reports that there are over 63,000 registered sex offenders in California!
This Section of the California Penal Code is for any person who has plead guilty or has been found guilty of a listed Sexual Offense and lives, works or goes to school in California.
The offenses that require registration are numerous and require reading more than one section of the code to fully understand who must register under this code. 
See the section(s) that list who must register
To read Section 290 of the California Penal Code in its entirety on the State of California's Website you can go to the Codes Section of  the California website.
1.  Go to State website (address link at end)
2.  Select "Penal Code" from list of Codes
3.  In the Search Box enter 290 and then Select "Search"
4.  Select from the returned list the one that covers Section 290 to 291
Also check Welfare and Institutions Code Secition 6600