Uranus
Uranus governs sudden change, freedom and anything that breaks the usual order. It was the first planet discovered with a telescope, in 1781.
Governs
Uranus describes the area where a person can't stand restrictions and where unexpected turns happen. It is associated with inventions, technology, independence, originality, and also with abrupt breakups.
Its cycle is 84 years, about seven years in each sign. So the sign of Uranus is the same for everyone born within a span of several years: it is a "generational" planet, and what carries individual meaning is primarily its house and aspects.
In the signs and houses
The sign of Uranus describes not the person but the generation: where exactly that generation breaks the rules.
The house of Uranus is the personal part: where a particular person can't tolerate predictability. In the fourth, moves and an unconventional family; in the tenth, a career that advances in leaps.
Strong and weak placements
Uranus was made the ruler of Aquarius after its discovery; classical astrology made do with Saturn, and some traditional schools still do.
This is an important detail: the three "outer" planets, Uranus, Neptune and Pluto, entered astrology only after their astronomical discovery. In other words, the system was extended as a science it doesn't use made progress.