A “movement” is what you’ll find inside a watch powering it, and companies that design and produce their own in-house are given a good deal of respect in the industry. Many watchmaking concerns, however (and especially many micro-brands), rely instead upon a small number of tried-and-true calibers from several companies whose specialty is in producing movements themselves, rather than complete watches.
Utilizing these commonly available, outsourced movements allows the watchmakers to keep costs down and introduce a known quantity into the equation of watchmaking; these movements are relatively inexpensive, commonly available, and comparatively hassle-free to service.
You’ll also find other versions of said calibers with tweaks in their names and features (day-of-the-week display, GMT, etc.), but what follows are some of the most well-known and commonly utilized automatic watch movements available today in their basic forms — along with examples of watches that use them:
ETA 2824-2

Doxa Sub 300
One of the most ubiquitous and well-known automatic calibers available today, the ETA 2824-2 is based upon the Eterna 1247, which was first produced in 1955. The 2824-2 itself has been in production since 1982 and is available in four grades: Standard, Elaboré (improved), Top and Chronometer — as the grades increase, so does the movement’s accuracy, finishing level and price. ETA, a wholly-owned subsidiary of the Swatch Group, has developed a new generation of upgraded movements for its group brands, while third parties primarily use legacy movements like the 2824.
Features: Hours, minutes, sweep seconds, date window
Diameter: 25.6 mm
Height: 4.6 mm
Jewels: 25
Vibrations Per Hour: 28,800 (4 Hz)
Hand-Winding Possible: Yes
Hacking: Yes
Power Reserve: 38 hrs
Country of Manufacture: Switzerland