What is Parliamentary Sovereignty?

The traditional definition of parliamentary sovereignty is that there is no legal limit to the laws that can be enacted by Westminster Parliament. All restraints flow from political checks and balances and conventions as opposed to any legal restrictions. 

The UK courts cannot strike down or refuse to apply Acts of Parliament because there are no external constraints upon what Parl can do. Additionally, current parliaments cannot entrench future parliaments as this would place a restriction on that future parliament's sovereignty. There are different models of parliamentary sovereignty argued by academics and even the idea that parliament is not actually sovereign at all.