Since the American Revolution happened in the dark days before there was an internet - and even before telephones - organizing colonial opposition to the British was a little tricky. I don't want to make you cry, but these clowns didn't even have dial-up. The solution was to send out riders bearing letters to inform Colonists in other areas what was going on - these became known as committees of correspondence. (Correspondence being a fancy name for letters - if you did not know this I am amazed you have even read this far. Actually, I'm amazed you even can read this far.)
Samuel Adams created one of the first Committees of Correspondence in Boston in 1772 - in particular, he wanted to keep people outside of Boston informed about town meetings, so the governor couldn't invite only his friends to meetings. That would have been less a meeting, more a dinner party.
Perhaps unsurprisingly, Adams' committee worked so well that everyone started doing it. Eventually all of the colonies had their own committees, focused on presenting a united front against British-imposed taxes, and supporting boycotts of British goods.
Really, Adams should have patented the idea. He could have made a fortune.
This was the army that George Washington led in the American Revolution, made up of various regiments supplied by the states. The army was officially established by the Continental Congress in June of 1755, shortly after the Siege of Boston began. In fact, it was formed specifically to deal with the Siege of Boston, which at the time was being carried out by the various militia who had fought at the Battles of Lexington and Concord.
The Continental Army was disbanded in 1783 after the Revolution was formally ended - possibly because people agreed the civilian militias were all the colonies needed to defend themselves - but possibly also because Congress couldn't afford to pay them. My money's on that last one.