A skyscraper is a tall building
A skyscraper is a building that is higher than an apartment block, but how high it is varies by country or region. There are no rules on when something is a skyscraper, however, it must be a building with floors intended to work or live in (i.e. no mast or view tower). Often a building is called a skyscraper if it determines the skyline of a city, for the Netherlands you are talking about a building of 100 meters or higher. Skyscrapers are mainly building in places where the land price is expensive, because with relatively little land you can make a lot of space to live or work.
Below are some pictures of skyscrapers