Short answers, pulled from the story.
The Habsburg dynasty began with Radbot of Klettgau building Habsburg Castle in the late 10th century. King Rudolf I assigned the Duchy of Austria to his sons at the Diet of Augsburg on the 2nd of May 1282, which established the Austrian hereditary lands.
Charles V ruled the largest territorial extent ever held by the Habsburg empire from 1519 until 1556. He inherited three major territories including Spain, the Burgundian Netherlands, and the Holy Roman Empire before dividing the house in 1556.
The Hereditary Lands covered most modern states of Austria and Slovenia plus parts of northeastern Italy. The Imperial Free City of Trieste and Margraviate of Istria formed part of this western bloc alongside the Archduchy of Austria, Duchy of Styria, Duchy of Carinthia, and Duchy of Carniola.
Leaders arrived at the famous Austro-Hungarian Compromise of 1867 to create a dual monarchy system where Austria-Hungary became two states under one crowned ruler. This agreement linked joint foreign and military policy while maintaining separate internal governance between the Kingdom of Hungary and other Habsburg lands.
Defeat in World War I triggered the disbandment of the entire monarchy in late 1918 after pressure from various ethnic independence movements. Charles I ruled from 1916 until 1918 before exile followed as significant territories were ceded to Romania and Italy through subsequent peace settlements.