In this modern age, the ‘chaarvaaka darshanam’ is called ‘materialism’. chaaru vaak – chaarvaaka-means pleasing words. Traditionally it is believed that bruhaspaty the preceptor of gods created and propagated this siddhaanta among demons so that they become weak with materialistic pleasures and become weak morally and then easily be defeated by gods, who possess shuddha saatvika guna and are engaged in loka-kalyana. But slowly this siddhaanta became attractive and percolated into human behavior. chaarvaaka siddhaanta promotes- 

यावज्जीवेत् सुखम् जीवेत् ऋणं कृत्वा घृतं पिबेत् ।

भस्मीभूतस्य देहस्य पुनरागमनं कुतः ।|

Yaajjeevet sukham jeevet runam krutvaa ghrutam pibet |

Bhasmeebhootasya dehasya punaaraagaman kutah ||

Live happily as long as you live and enjoy in this world only. Even by taking debt, you must drink ghee i.e. costly enjoyments should be obtained. Because, who knows what happens after death? when the body is burnt to ashes, how it can come back? This is main preaching of chaarvaaka mata/philosophy. It is also called as lokaayata mata.

Each veda shaakhaa got an upanishat at its end. So, as many veda shaakhaas are there so many upanishats are there. Out of them 1008 upanishats are available now. Out of them 108 upanishats are important. Out of them 10 upanishats are very important in teaching brahmajnaana. Jagadguru shree aadi shankara bhagvatpaada wrote bhaashyam/commentaries for those ten upanishats.

In this section a few important upanishats will be taught which essentially form the fundamental blocks for the common man to understand the knowledge encrypted in the vedas.  The Knowledge of self-realization and the concepts of brahma and aatmaa will eventually lead to higher enlightenment and lead to moksha.

upanishats can be categorized into:

1. vedaanta upanishats
2. yoga upanishats
3. shaiva upanishats
4. vaishnava upanishats and
5. shaakteya upanishats.

The vedanta upanishats have 11 important upanishats.

1. eesha, 2. kena, 3. katha,4. prashna,5. mundaka,6. maandookya, 7. aitareeya,
2. taittiriya 9. chaandogya, 10. brihadaaranyaka, 11. shvetaashvatara.

They are commented on, by various aacharyas starting with aadi shankaraachaarya.

Brief Note on all the above important upanishats, is given here under, including two more upanishats– namely kausheetakee upanishat and maitraayaneeya upanishat.