Vedaant Sootra
Name of the work by Baadaraayan, also called Brahm Sootra, claiming to present the entire contents of the genuine Upanishad in the form of 555 short aphorisms in four chapters. [By comparison Shree Mad Bhaagvat contains 18,000 full Shlok.] The term Vedaant has recently become more popular meaning "the Final Message of the Ved".
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It is sometimes possible that we forget the real meaning of some of the common and popular terms. The term Vedaant is one such example. While some people understand the term as useless discussion or some thing not understandable, others consider that all that concerns Adhyaatm is Vedaant. Vedaant means the last part of Ved (Ved + Ant). Among the parts of Sanhitaa, Braahman, Aranyakaa and Upanishad, the last one is Upanishad. According to Meemaansak, the part of Ved which relates to its definite meaning (Vedaarth) is Vedaant. "Ant" also means Nirnaya (decision). (Vedo Vedaarth, tasyaanto nirnayah).

According to Meemaansak - "Mantraashch braahmanam cha Vedah" - Mantra are helpful for Yagya etc, and Braahman provide us the rules, explanations, stories, instances etc. While the Aaranyak are the discussions part and these end in the Upanishad. The discussions on the Braahman constitute the Poorv Meemaansaa and those that discuss on the Aaranyak and the Upanishad constitute the Uttar Meemaamsaa. Uttar Meemaansaa is also called as Vedaant Meemaansaa which indicates that these discuss the Upanishad.

Mantra Braahman which are useful for the Yagya and other rituals are termed as Karm Kaand; and
the Aaranyak - Upanishad which do not attach importance to the Karm are called Gyaan Kaand.

The number of Upanishad according to Muktikopanishat is 1108.
According to Weber, the number is 235.
As per Max Mueller, it is 170.
But all these are not parts of the Ved and so they are not Vedaant.

As per tradition and from times immemorial, the number of Upanishad which are considered as as parts of the Ved is only 13.
Six Aaranyak Upanishad, 4 Sanhitaa Upanishad and 3 independent Upanishad.

Aitareya, Ken, Chhaandogya, Taittireeya, Brihadaaranyak, and Kausheetikee - these 6 Upanishad are Aaranyak Upanishad.
Eesh, Kath, Shwetaashwatar and Mytraayan - these 4 Upanishad are the Sanhitaa Upanishad.
Mundak, Maanddookya and Prashn - these 3 Upanishad are 3 independent Upanishad.

Shankar recognized only 10 of these and excluded Kausheetikee, Shwetaashwatar and Mytraayan in his Bhaashya although he has quoted from the first two Upanishad in his Sootra Bhaashya. Mytraayan is not touched either by Shankar or Baadaraayan.

The Vedaant thus depends on these Upanishad and derives strength from the Brahm Sootra of Baadaraayan.
When one looks casually at the Upanishad, they look like encouraging different philosophies.
However, if a detailed study is made, these reflect a single philosophy only as demonstrated by Baadaraayan.
This was later elucidated by Shankar.