Weltpolitik means 'world politics.' It was the idea that Germany wanted its 'place in the sun' - in other words, an empire. Germany wanted influence in world affairs and to become a world power like Britain.
When was Weltpolitik implemented?
Weltpolitik was implemented from the 1880s, but became more noticeable after 1900 as Germany pushed for an empire and became more involved in international affairs.
Why did they have Weltpolitik?
Kaiser Wilhelm II was jealous of the empire held by his cousin, George V of England. He longed to rule a country like that of his beloved grandmother, Queen Victoria. Weltpolitik would make Germany stronger and more powerful internationally.