The trachea is also called the windpipe and it connects the mouth to the lungs.   It is distinguished from the nearby esophagus by the presence of cartilage rings which prevent the airway from collapsing.   At the top of the trachea is the larynx, or the voicebox.

The photo below shows a comparison between the visual appearance of the trachea and the esophagus, which is flexible soft tissue.  The esophagus usually lies to the side or behind the trachea.