It doesn't take long to mark two crosses on a ballot paper, but they are of immense significance. By marking these crosses, the voter is taking the central decision in a democracy: who should govern?
This right to participate in elections is guaranteed by the constitution: the Basic Law stipulates that "All state authority is derived from the people." Article 38 states that elections must be "general, direct, free, equal and secret".
62 million eligible voters
Elections to the German Bundestag are generally held every four years. The last election was in autumn 2013.
Voters will have two decisions to make: their "first vote" determines their choice of constituency candidate, with the candidate who wins the most votes being elected, regardless of how his or her party performs overall. These constituency seats ensure that every region in Germany is represented in the Bundestag.
The second vote is decisive
With their "second vote", voters determine the relative strengths of the parties in the Bundestag. The second vote is therefore the decisive vote, as it dictates which parliamentary group or coalition of parties will have a majority allowing them to elect their preferred candidate as Federal Chancellor.
If a party fails to meet the requirement that it receive more than five per cent of all votes cast nationwide (also known as the "five per cent clause"), it is not represented in the Bundestag - unless the party has won at least three constituency seats, in which case it is taken into account in the distribution of seats to the parties' lists in the individual Länder (federal states).
The German electoral system is based on proportional representation, but contains elements of first-past-the-post. Who holds the majority in the Bundestag is, however, initially determined by the number of second votes won by the individual parties. Half of the total of 598 Members of the Bundestag are politicians who won the most first votes in one of Germany's 299 constituencies. The other half of the Members are elected via party lists in the individual Länder.
These lists are drawn up by the parties, which nominate candidates they consider to be particularly well-qualified to serve in Parliament - or who are believed to be popular with the electorate. The places at the top of the list are generally considered to be "safe", with election likely.
A certain degree of risk remains, however: if the number of constituency seats won by a party is as high as the number of seats it is entitled to according to its share of the second votes, then even the top candidate on the list will not be elected - unless he or she has won a constituency seat.
The number of constituency seats won is extremely significant, because it can have a major impact on the composition of Parliament, which is otherwise fixed according to the share of second votes won. If a party wins more constituency seats than it is entitled to according to its share of the second votes, it nonetheless keeps these additional seats, known as "overhang mandates". The other parties then get additional seats also.
The Bundestag currently has 630 Members. Parliament will convene for the first time no later than 30 days after the Bundestag elections (Article 39 of the Basic Law) to elect the President of the Bundestag and adopt its Rules of Procedure (Article 40 of the Basic Law).