Ernesto Guevara De La Serna was born in Rosario, Argentina in 1929 and grew up under the rule of dictator Juan D. Peron and his popular reforms.
He became a physician and after traveling through South America on his 23rd birthday, he started to develop Marxist ideas due to the extreme poverty and oppression Latin America suffered under the rule of the US and its Latin collaborators.
He spent some time in Mexico where he met Cuban exile Fidel Castro and other dissidents that hated the US control of Cuba through dictator Fulgencio Batista.
Ernesto was called "Che" since this is the way Argentineans call each other ( a slang word for "pal")
Che, Fidel and 80 other revolutionaries traveled from Mexico to Cuba in an old boat called "Grandma".
The 26th of July movement started its guerilla war against Batista in the Sierra Maestra, hiding, fighting and training from there.
When the revolution was won, Fidel and the revolutionaries took La Habana and took over the country. Che worked in many government jobs, including Minister of Industries and head of the National Bank (which he really didn't know much about)
Che was a man of the people, and believed that the success of the Cuban Revolution should be repeated in the entire world. He helped some revolutionaries in Congo, but their guerillas lost their battle.
Che then went to Bolivia, where he also unsuccessfully led the guerrillas. He was captured and wounded in the Bolivian mountains by the national army and some CIA operatives who believed him to be a national threat (specially because of his participation during the Bay of the Pigs and Cuban Missile crisis). Che was executed and buried in 1967 (he was 38 years old)
This is just a summary of his life. He did many different things and wrote several books discussing his thoughts on Marxism, Global Justice, economy, etc.
I suggest you should look more information in bios about him, the internet (www.el-comandante.com is a good source) and his own works like "Motorcycle Diaries", "Bolivian Diary" "Global Justice", etc. (right now I'm reading "Che speaks to the youth.")
He is known in most of the world. Unfortunately, Capitalism used him as a merchandising symbol, despite his fervent Marxism. T-shirts, mugs, posters, etc. are used by lots of people, including those who don't even know who he is. Sad.
This picture is his most famous.