Retractable and extensible trailer with folding ramp

A retractable and extensible trailer comprising: a base assembly; a moveable top assembly moveably attached to the base assembly and configured to be infinitely adjustable between a lowered position and an upper position; a trailer substructure in communication with the base assembly; a base front and/or rear folding door located at the front and/or rear of the base assembly and in rotative communication with the trailer substructure. The base front and/or rear folding door comprises: an upper ramp in rotative communication with the trailer substructure; at least one locking plate in fixed communication with the upper ramp; at least one connector plate in rotative communication with the at least one locking plate; and a lower ramp in fixed communication with the at least one connector plate.