Spilt and build a house

[Idan Cohen]

I would appreciate someone helping with this matter:

I live in California and I know that there is high demand for housing in all the Bay Area, and I would like to know if I can buy a house then completely demolish it and build apartment building? is there any restriction? does the house need to look like all the houses in the neighborhood or I can change the appearance completely ?

If there is a restriction and I can't build a apartment building can I a house and take over all the property (Include the back yard) and split the house to 4, 1 or 2 bedroom apartments? this way I can rent it to 4 different tenants 

I'm just getting into real estate so forgive me if my questions does not make sense.

Thanks!