The mechanic uses both electronic means of gathering data and their senses. Their job may involve the repair of a specific part or the replacement of one or more parts. Basic vehicle maintenance is a fundamental part of the mechanic's job in some countries. Preventative maintenance is also a fundamental part of the mechanic's job, but this is not possible in the case of vehicles that are not regularly maintained by the mechanic. One misunderstood aspect of preventative maintenance is "scheduled replacement" of various parts, which occurs before failure to avoid far more expensive damage. Because this means that parts are replaced before any problem is observed, many vehicle owners will not understand why the expense is necessary. With the rapid advancement in technology, the mechanic's job has evolved from purely mechanical, to include electronic technology. Because vehicles today possess complex computer and electronic systems, mechanics need to have a broader base of knowledge than in the past. The term "auto mechanic" is being used less and less frequently and is being replaced by the title "automotive service technician". Fading quickly is the day of the mechanic, who needed little knowledge of today's computerized systems. Most automobile dealerships now provide sophisticated diagnostic computers to each technician, without which they would be unable to diagnose or repair a vehicle.