An auto mechanic (or car mechanic in British English and motor mechanic in Australian English) is a mechanic who specialises in automobile maintenance, repair, and sometimes modification. A mechanic may be knowledgeable in working on all parts of a variety of car makes or may specialize either in a specific area or in a specific make of car. In repairing cars, their main role is to diagnose the problem accurately and quickly. They often have to quote prices for their customers before commencing work or after partial disassembly for inspection. The mechanic uses both electronic means of gathering data as well as their senses. Their job may involve the repair of a specific part or the replacement of one or more parts as assemblies. Basic vehicle maintenance is a fundamental part of a mechanic's work in some countries, while in others they are only consulted when a vehicle is already showing signs of malfunction. Preventative maintenance is also a fundamental part of a mechanic's job, but this is not possible in the case of vehicles that are not regularly maintained by a 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. Lately, the term "auto mechanic" is being used less and less frequently and is being replaced by the euphemistic title “automotive service technician”. Fading quickly is the day of the 'shade tree mechanic', who needed little knowledge of today's computerized systems. Due to the increasingly labyrinthine nature of the technology that is now incorporated into automobiles, most automobile dealerships now provide sophisticated diagnostic computers to each technician, without which they would be unable to diagnose or repair a vehicle. In the United States, several programs and schools that offer training for those interested in pursuing competencies as an automotive mechanic, or as an auto technician already exist (see Wyoming Technical Institute). A few of the aspects usually taught those studying for this career are: powertrain repair and diagnosis, emissions, and suspension. Most mechanics are ASE certified, which is a standardized method of testing skill level.[citation needed] The National Automotive Technicians Education Foundation (NATEF) is responsible for evaluating technician training programs against standards developed by the automotive industry and recommend qualifying programs for certification. NATEF certifies programs in four different categories: automotive, auto body, trucks (diesel technology) and alternative fuels. Automotive Youth Educational Systems (AYES) is a non-profit partnership of automotive manufacturers, dealers, and high schools/tech prep schools that aims to encourage young people to consider careers in retail automotive service, and prepare them for entry-level career positions or advanced studies in automotive technology. The technology used in automobiles changes very rapidly and the mechanic must be prepared to learn these new technologies and systems. The auto mechanic has a physically demanding job, often exposed to temperature extremes and well as lifting heavy objects and staying in uncomfortable positions for extended periods as well as exposure to gasoline, solvents and other toxic chemicals. In Australia, an apprentice works under one or more qualified mechanics for a period of four years. During that time, they attend a Technical and Further Education (TAFE) college one day per week for three years. In some states, mechanics are required to be trade qualified and hold a tradesman's certificate in order to work as a mechanic, and the workshop in which they work is required to have a workshop license. In other states, no such licensing is required.