subject of causative
Marks the person made to do something in causative constructions. The causer is marked by が or は.
母は子供を買い物に行かせた。
The mother made her child go shopping.
Marks a time span during which an action occurs, often with verbs like 過ごす, 暮らす, 生きる. Not used for a specific point in time.
夏休みを海外で過ごした。
I spent the summer vacation abroad.
object of desire/like/hate
Marks the object of emotions or desires with adjectives like 好き, 嫌い, 欲しい, and verbs like 望む. In modern Japanese, が is also common for these, but を is used especially when the object is clearly acted upon or in subordinate clauses.
See also: が
私は猫を愛している。
I love cats.
I've been wanting a new pair of shoes.
The teacher made the student stand in the hallway.
I walk through the park every evening.
I left home at seven in the morning.
I drink coffee every morning.
I spent the summer vacation with my family.
If you go along this road, you'll reach the station.
I graduated from university last year.
が marks the subject or the object of potential/desire predicates, while を marks the direct object of transitive verbs, a path, or a departure point—learners often mix them up with 好き/欲しい and with motion verbs.
に marks a destination or point of contact (乗る, 着く) while を marks the space traversed or the point of departure with the same kind of motion verb (通る, 出る), so learners easily swap them.
Kana-only particle; no kanji form exists.
The particle を derives from Old Japanese particle を, which originally marked an exclamatory or emphatic object. Its modern use as a direct object marker developed early and has remained stable.