What is "muktika"

The Muktikā ( Sanskrit: "deliverance") refers to the canon of 108 Upaniṣads. The date of composition of each is unknown, with the oldest probably from about 800 BCE and the youngest probably composed after the 15th-century CE. The Principal Upanishads were composed in the 1st millennium BCE, most Yoga Upanishads composed probably from the 100 BCE to 300 CE period, and seven of the Sannyasa Upanishads composed before the 3rd century CE.