How do I deal with quotes ' in SQL

I have a database with names in it such as John Doe etc. Unfortunately some of these names contain quotes like Keiran O'Keefe. Now when I try and search for such names as follows:

SELECT * FROM PEOPLE WHERE SURNAME='O'Keefe' 

I (understandably) get an error.

How do I prevent this error from occurring. I am using Oracle and PLSQL.