A personal force field was a force field that protected an individual from harm.
In the late 2260s and the early 2270s, life support belts were used by Starfleet personnel to emit a personal force field which supplied the wearer with the appropriate atmosphere and protected them from the elements. (Star Trek: The Animated Series)
In 2369 during the Ancient West holographic program, holodeck safety protocols were non-functioning due to an experiment by Lieutenant Commanders Geordi La Forge and Data in engineering. As a result, Worf created a makeshift force field generator using his combadge's energy cell as a power source. As it was highly unstable, the field wouldn't last more than fifteen seconds. Before it dissipated, the field deflected several projectiles fired by Frank Hollander. (TNG: "A Fistful of Datas")
Borg drones utilized personal force fields which were capable of blocking directed energy particle weapons such as phasers and phase-pistols. (TNG: "Q Who", ENT: "Regeneration") After traveling through time from 2373 to 2063, Jean-Luc Picard used a holographic Thompson submachine gun projectile weapon which penetrated the shields of two Borg drones. (Star Trek: First Contact)
In 2377, B'Elanna Torres recalled that while in the Maquis, she and Tabor joked that the Bajoran must have his own personal force field, as he survived a dozen firefights unscathed. Tuvok, noting that the now-injured man yet lived, suggested the force field was still operational. (VOY: "Repression")