This video from Vittoria shows the manufacture of their tubular tires.
The tires shown in this video are “tubular” tires and are mostly used for track racing and professional road racing. As shown in the video, the tire casing is sewn around the tube.
The tire most cyclists are familiar with are “clinchers” — these are the usual bike tires where a tire is mounted over a tube on a bike rim. In spite of the extra effort required to repair and mount tubulars, they’re used in pro racing because, historically, tubulars have been lighter and safer than clinchers.