What is fatwa? Will Muslims target Donald Trump, Benjamin Netanyahu after Shiite clergy's decree? Salman Rushdie was stabbed after fatwa...

Is it now the duty of every devout Muslim to target US President Donald Trump and Israeli Prime Minister Benjamin Netanyahu after Iran's top Shiite cleric issued a 'fatwa' or religious decree against them? What is a 'fatwa' and how does it work? Does a 'fatwa' carry any significance now?