What is martial law and what happens if Trump imposes a similar order in US? Check details

Will US President Donald Trump impose a military law-type order after revoking Insurrection Act of 1807? Rumours online claim that US President Donald Trump could invoke the centuries-old Insurrection Act and declare martial law on April 20. The rumour originates from an executive order he signed on his first day in office, which hinted at the possibility of such steps within 90 days.