New technologies appear all the time. Right at this moment scientists are laboring away on the Herculean task of making an artificial cell, a challenge that for the first nine tenths of the 20th century many biologists would have dismissed as an impossibility. Just as important as new invention, though, is the translation of ingenuity into practice. This year's SCIENTIFIC AMERICAN 50 represents a testament to pragmatism. Many of the reports that have wowed the public on advances in nanotechnology or stems cells, to name just two, have taken a big step from graduate-level research toward becoming items for purchase at Wal-Mart or routine therapies at your local hospital.

A Korean researcher gained worldwide attention by achieving a 10-fold improvement in the number of stem cell lines derived from cloned human embryos. Japanese investigators created a solar cell that both generates and stores electricity. For the fourth year, the SCIENTIFIC AMERICAN 50 recognizes people, teams and organizations whose recent accomplishments, whether in research, business or policymaking, demonstrate leadership in shaping both established and emerging technologies.

In naming the winners of 2005, the magazine's editors and their expert advisers identified noteworthy trends related to technology ranging from polymer memory chips to a technique for regenerating damaged heart tissue. As you will see, the awards provide evidence once again that the application of new science, business acumen and policymaking skills not only can help build new machines but also can make a substantial difference in the way we all live.

Research Leader of the Year
Business Leader of the Year
Policy Leader of the Year
SA 50 Winners and Contributors
Trends in Research, Business and Policy