I had a question that asked when Hitler took power, and when was he removed from power.
The short answer is he became Chancellor of Germany in 1933 and committed suicide in 1945.
He came into power during the depression and while Germany was suffering of the weight of the Treaty of Versailles. The economy was a wreck, inflation was sky high, and Germany was under the thumb of France.
Hitler rose to the be the leader a right wing, ultra-nationalist party, the National Socialist German Workers Party. They were called Nazis for short. In the 1920s they just one of many parties in Germany. At first they weren't taken seriously. They were just seen as a fringe right wing group. Sort of like the Neo-Nazis or some ultra right-wing, ultra nationalist militia group today.
Because of the societal and economic upheaval in Germany, many Germans gravitated toward Hitler because he promised to fix Germany, and he blamed the Jews for all of Germany's problems.
He was elected as the leader of Germany's government, its Chancellor in 1933. It was a democratic and fair election. Germany had (and still has) a parliamentary system, so it's different than ours, but he was elected. After his election he slowly accumulated more power until he became the absolute dictator of Germany.
Sometimes we have this larger than life image of Hitler. Kids seem to think he was this evil genius. He was evil, but he wasn't a genius. He was just a better than average public speaker, who told the Germans that he was going to fix Germany and make it great again. In normal economic conditions and in a stable democracy with a tradition of minority rights, he probably never would have been able to grab as much power as he did.
People also think the Nazis were geniuses at management and technology. No. The Germans were geniuses at management and technology. The Nazis just took over and hijacked the most advanced society on earth and used it to advance their political and societal ends.
Another thing we hear a lot is that Hitler wanted to take over the world. As far as I can see that's not true. He said from the beginning that he wanted to take over Russia so Germany could expand. So no, we probably would not have been speaking German if we didn't go to defeat him in Europe. Everybody in Europe would probably be speaking German (or Russian depending on who won the war between Germany and Russia) but Hitler probably wouldn't have been able to take over the United States, even if he had tried.