Anthony Stark died in 1978, during a climactic battle between the Avengers (with an assist from the new group, the Guardians) and Ultron. Ultron had discovered a way to take control of the Iron Man armor and turn it against his comrades whatever Stark did to try to get control back. Facing their most powerful member and Ultron, the Avengers were on the ropes when Tony Stark used an emergency mechanical procedure to turn off every system in his armor. Without the pacemaker heart booster in his torso armor, Stark died and the suit died with him. The Avengers then went on to completely defeat Ultron--who has never reappeared.
Stark's executor and old friend Jim Rhodes took control of the Iron Man secrets and continued as Iron Man on an intermittent basis. But without Stark, Stark Industries began to go down the tubes. The Board of Directors started a lawsuit to gain control of the Iron Man secrets and managed to find a sympathetic judge who ruled that Stark had been developing his suit on "company time" and therefore the suit belonged to SI. Jim Rhodes has been said to have kept some of the secrets, but most he turned over to the corporation, who promptly licensed them to other corporations and the United States government, which was slow to try to contain the possible damage.
By 1981, battlesuit technology was well established all over the world, with legal and illegal users of the licenses making battlesuits. Rhodes obviously had kept several important secrets; most suits were bulkier and less efficient; but many other geniuses made their own adjustments to match or surpass Iron Man's abilities.
Jim Rhodes-Iron Man was killed with the rest of the Legion of Honor in 1983. Since then, Stark Industries has continued to maintain an Iron Man as company figurehead, but the various inhabitants of the suit have often been less than exemplary and have not lived up to the example set by Stark and Rhodes. Currently the inhabitant of the suit is a young woman who is said to be lobbying to have the name changed to Iron Woman, but with little success. The suit itself looks much as it has since Stark's death in 1978.
One thing Rhodes did before his death was establish the Men of Iron Foundation, an organization meant to help control the proliferation of battlesuits and establish a code of ethics for those who use battlesuits in the fight against crime and other evils. Most heroic battlesuit users belong, pay licensing fees for the use of whatever remains of Stark's technology, and subscribe and contribute to a newsletter circulated among them (usually through FORCE offices) that comments and elaborates on all the latest applicable technology. Copies of the newsletter are usually found in the lairs of power-suited villains.