What is meant by the idea of satyagraha?

Answer: Satyagraha's idea emphasized the power of truth and the requirement for truth in essence. It was suggested that if the cause is true, if it is a fight against injustice, then  physical violence is not necessary to fight the oppressors.
Satyagraha was able to win the battle through nonviolence without seeking revenge or becoming aggressive.

This can be done by appealing to the conscience of the oppressor. The general public, including oppressors, needed to be persuaded to see the truth, rather than being forced to accept it by violence. Through this vast and great struggle, the truth ultimately led to victory. Mahatma Gandhi believed that this nonviolent law could unite all Indians.

Gandhi's Satyagraha movement

• Returning to India, Mahatma Gandhi successfully organized the Satyagraha movement in several places.  
• In 1917 he traveled to Champaran, Bihar, urging farmers to fight the oppressive plantation system.
• In late 1917 he organized another Satyagraha movement to help farmers in the Kheda district of Gujarat, who were suffering from crop failures and epidemics. Farmers in the village of Keda were unable to pay their income and demanded easing of income collection.
• In 1918 Mahatma Gandhi went to Ahmedabad to organize the Satyagraha movement among the  workers of the spinning mill.