1) The concept of sovereignty refers to the supreme authority and power of a state to govern itself, make decisions, and control its own territory without interference from external forces.

2) The concept of proportional representation, used in some electoral systems, aims to ensure that political parties' representation in government aligns more closely with the proportion of votes they receive from the electorate.

3) The Alps, located in Europe, are a popular destination for skiing, mountaineering, and hiking.

4) The human brain has a storage capacity equivalent to around 2.5 petabytes, which is roughly equivalent to three million hours of TV shows.