I'd like to add a follow up question: Did guards actually exist in times of peace? There is a common trope in videogames of a castle being heavily defended by guards, but is this actually true?

Follow up question in regards to villages, were there typically constables/sheriffs/house guards of a lord? Or would it be a militia? I imagine a guy in a tower with a bell for a decent sized village... is that way off?

follow up question on the armour: Did they have to buy their own armour and if not were they allowed to keep it after their duty?