Parental Responsibility (or PR as it is known) is a legal status that is automatically conferred upon mothers and usually on fathers providing that dad was at some time either married to mum or is named on the birth certificate and the child was born after 1st December 2003.
Parental responsibility means that the holder of PR has all rights, duties, powers and responsibilities of a parent and the holder of PR has the authority to act as parent.
Whilst in normal circumstances only parents and step parents can acquire parental responsibility either by agreement or by court Order (called a Parental Responsibility Order).You can also acquire PR if you have Child Arrangements Order, stipulating a child lives with you.