The haiku is a type of Japanese poetry with three lines. The first line has five syllables, the second has seven, and the third has five. The haiku grew out of the hokku, the first three lines of a tanka, which is a longer poem. In the 1600s, the haiku became a distinct type of poetry.
Words on the page (5)
Meaning hidden in between (7)
Ready to be found (5)
The haiku can be seen as a seasonal poem, which is traditionally about nature. The theme isn't only about nature, though; it's real nature mixed or juxtaposed with human nature. So you need to go further than just a surface-level understanding of the genre, and you'll find something worth reading.