It is a sign of spring, a fertility symbol and the public self-portrait of a place all in one. Which of these layers stands out depends on the beholder; all three are true at the same time.
Spring and fertility
The oldest layer is that of the spring rite. The green, upright tree stands for vital force, growth and the victory of the warm season over the cold. The wreath at the top is an old fertility sign. In this meaning the maypole belongs to a long line of spring customs.
The community
The most visible meaning lies in the guild emblems. They show the trades and clubs of a place and make the tree a directory of the community. To read a maypole is to read who lives and works there. The tree is an expression of pride and sometimes of a small contest over who has the taller, finer tree.
The contract in wood
A third meaning arises only through maypole stealing: the tree is also a pledge. As long as it is not standing, it may be stolen and returned for a ransom. In this meaning the maypole is less a symbol than a social game with firm rules that holds a neighbourhood together.
Why it is called a maypole
The name is the simplest part: the tree is raised in May, traditionally on 1 May, marking the start of the warm season. More on its origins on the page about the tradition of the maypole.