Tifa Lockheart was born in the mountain village of Nibelheim. Her father, the town's mayor, insisted on her being homeschooled, as opposed to being sent to some far off school. Various aptitude tests issued by Shinra Educational Corps., found her to be a bright student who excelled in language, math, and writing skills. The townspeople reported her to be friendly and outgoing, with a perpetually positive attitude. Tifa was also raised by her father, after her mother died at age 8.
Tifa was considered to be a very adventurous girl, and at a young age, she had earned the title of being the 'best guide to the mountains of Nibelheim' around. It was because of these skills that she was recruited to be the leader of the ill-fated expedition into the Mt. Nibel Reactor (Nibelheim Incident) with Sephiroth and three other soldiers. She led them up to the reactor where Sephiroth reportedly went mad. The next day, Sephiroth burnt down the town of Nibelheim and killed Tifa's father. When he went up to the reactor, she followed, and was subsequently stabbed by him. It is unknown how she recovered, as witnesses report that her wound appeared to be a near-fatal one.
After the incident, Shinra's Intelligence agencies lost track of Tifa Lockheart over the next few years, but it appears that during this time, she moved to Midgar, and set up a small pub in the Sector 7 Slums. There, she met up with Barret Wallace, the former Corel coal miner and leader of the Shinra resistance group, AVALANCHE. Tifa sided with Barret, and joined his little band of rebels. She would later reunite with Cloud Strife, the Shinra Guard who had been listed as dead/missing in action from the 'Nibelheim Incident', and who was also a childhood friend of hers. All of them would later go on to blow up 2 of Midgar's 8 reactors, to raid the Shinra Headquarters, attack and wound Reno, of the Turks, highjacking 'The Highwind' military aircraft, and have been accused of causing the summoning of Meteor. In addition, Tifa was also able to escape from her own execution, which was to be conducted by Scarlett of Shinra's Weapons Development Dept.
Tifa Lockheart is considered armed and dangerous, and should only be approached with heavy back-up by qualified members of Shinra's police force.