The Tsar’s abdication in 1917 was a Direct conscuence of the February revolution. He was forced to give his Position to someone else and as his child had a very critical health situation He gave it to his brother, who decided not to take it and ment the end of tsarism.
In February 1917 people in Petrograd went to the streets on a strike in order to make the tsar listen to them but it was mainly a peaceful "revolution". When the news arrived to the tsar, as he was weak and never trained to be a tsar, his only decision was to make no decision over it and he was only looking forward to meet with his family in Petrograd, therefor the army decided to react in an aggressive way pressing the people leading to a bast amount of deaths and injuries. While the tsar tried to reach to Petrograd by train, revolutionaries took the railway and he was not able to reach Petrograd. People near the tsar from the government told his, in order to preserve tsarism he should abdicate and by the 1st of March papers were signed for his abdication leaving his brother the charge. The next day his brother refused to take his position and this meant the end of tsarism. People in the cities celebrated with red flags and patriotic hims. But all of this wouldn't had happened if the tsar hasn't lost his popularity among people, the reasons for this were: Russia's performance in war, the war at home, rasputin's influence, Nichola's refusal to make concessions, the peasants, the bolsheviks, soldiers and the ruling classes; i'll be explaining only the ones that in my opinion were the most important ant at the time.
During the 1st World War Russia made a very bad performance loosing territories and most importantly loosing many Russian lives. One Russia entered the war, the tsar was cheered and people loved him although the bad prepared army, the single railway system and bad communication that leaked Russia's plans helping germany to know what they were going to do and anticipate, made the tsar look incompetent and weak towards modern war.