( CNN ) -- On the backs of iPods , iPhones and iPads , and on the bottom of Mac laptops , an inscription reads : `` Designed by Apple in California . Assembled in China . '' The parts themselves come from more than 150 companies from various parts of the world . The majority of those antennas , glass , metal , sensors and silicon are manufactured overseas . How Apple finds parts and manufactures its products , almost entirely abroad , is standard protocol in the technology industry . Electronics companies say Asian manufacturing plants are more affordable and more versatile than those found anywhere else in the world . But as the most valuable tech company in the world , Apple is seen by many as a role model in business . And its reliance on cheap overseas labor -- most notably at factories in China run by manufacturer Foxconn -- has come under increased scrutiny in recent media coverage by CNN , The New York Times and other outlets . Foxconn , owned by Hon Hai Precision Industry , counts Apple among its business clients , which also include Amazon.com , Hewlett-Packard , Microsoft and many other tech giants . Apple has reported violations at its facilities , and Foxconn has come under fire for a slew of worker suicides in 2010 and conditions that workers-rights groups say are inhumane . Workers at Foxconn and other plants in Asia must stay busy to keep up with the world 's seemingly insatiable demand for Apple products . During the last three months of 2011 , Apple sold 37 million iPhones , 15.4 million iPads , 15.4 million iPods and 5.2 million Mac computers , according to the company 's financial report . That netted Apple $ 46.3 billion in revenue and $ 13.1 billion in profit , which is double what Apple made during the same period a year before . Where does all that profit come from ? Take the iPhone , for example . The iPhone 4S sells for $ 199 if the customer signs a two-year cellular contract . But AT & T , Sprint Nextel and Verizon Wireless pay Apple much more for the phones in order to sell them at a lower price , a process called subsidizing . To get a so-called `` unlocked '' or contract-free iPhone , expect to pay at least $ 649 to Apple . The costs of parts and manufacturing for Apple 's iPhone 4S is estimated to be $ 196 , according to industry research firm IHS iSuppli . That 's $ 453 less than Apple charges for a contract-free phone . Marketing and research can add up , but no matter which way you cut it , Apple is making a sizable profit on each phone it sells , said iSuppli analyst Tom Dinges . Apple has more than 60,000 employees , most of whom work in its retail stores . To build parts and assemble products , Apple has a long list of partners . That 's partly done to avoid being dependent on any one manufacturer and to get favorable deals on each part from the many competing companies . Still , Apple tries to minimize the number of companies with which it signs deals , Dinges said . That way , Apple wields more influence because it 's among the biggest-spending clients , he said . `` They 'd rather be a mile deep in a supplier than divide the business up amongst five , '' Dinges said . `` You 're going to take care of your biggest customers first . '' In its supplier report , Apple says 156 companies account for 97 % of the money spent on materials , manufacturing and assembly for its coveted gadgets . When the client is a powerhouse like Apple , winning a contract to be one of those 156 is a major event . In Wall Street parlance , it moves stock . Being anointed by Apple boosts a supplier 's credibility , but Apple is a shrewd negotiator , from how it develops an iPad to how it leases or builds the retail store it 's sold in . This reportedly forces Apple 's partners to push workers and cut corners in order to wring profits . Apple told CNN in a statement that its expectations for suppliers to operate responsibly increase each year . Apple says it conducted 229 audits of suppliers last year and reported its findings publicly online . `` We care about every worker in our worldwide supply chain , '' Apple said in the statement . `` We insist that our suppliers provide safe working conditions , treat workers with dignity and respect , and use environmentally responsible manufacturing processes wherever Apple products are made . Our suppliers must live up to these requirements if they want to keep doing business with Apple . ''
The parts and manufacturing for Apple products mostly happens overseas . Comment: Apple has more than 150 suppliers and manufacturers for its products .