* Old World monkeys (like baboons, macaques, and colobus monkeys) have opposable thumbs that allow them to grasp objects with precision. This is important for their ability to manipulate objects, including food and tools.
* New World monkeys (like spider monkeys and howler monkeys) have a different type of grasping ability. They often have prehensile tails, which can be used like a fifth hand. Some New World monkeys also have thumbs, but they are not as fully opposable as those of Old World monkeys.
So, it depends on the type of monkey. Some monkeys have highly developed opposable thumbs, while others have different adaptations for grasping.