The Char Dhams consists of the most important Hindu pilgrimage sites and has not been constant but changes based on the actual pilgrimage practice.
In the 8th century, the famous reformer and philosopher, Shankaracharya grouped the Hindu pilgrimage circuit into 4 sites namely the Char Dhams which originally consisted of four important temples,


>> Puri (in Orissa) - the place where Lord Krishna took an avtar as Jagannatha.

>> Rameshwaram (in Tamil Nadu) - place where Lord Rama built a bridge accross to Lanka.

>> Dwarika (in Gujrat) - was the dwelling place of Lord Krishna.

>> Badrinath (in Uttrakhand) - Goddess Lakshmi took the form of the berries to provide sustenance to Lord Vishnu during his long penance in the harsh Himalayan climate.

So these were the original Char Dhams stated by Shankaracharya. But with the changing times and developments around the intractable inclines of Himalayas, new paths opened up and it became easy to go to places that were once sought impossible. This altogether changed the Hindu pilgrimage culture and the new Char Dhams were recognized which are all located in the Gharwal section of Uttrakhand ---

>> Yamunotri (Uttarkashi district) - the source of the Yamuna River and the seat of the goddess Yamuna.

>> Gangotri (Uttarkashi district) - the source of the Ganga River and seat of the goddess Ganga.

>> Kedarnath (Rudraprayad district) - where a form of the Hindu god Shiva is venerated as one of the twelve jyotirling(linga of light).

>> Badrinath (Chamoli district, Uttrakhand) - the seat of the Hindu god Vishnu in his aspect of Badrinarayan.

So Badrinath has always been there in the Char Dhams and also is the most vital of all the others.

Who knows the Char Dhams may switch again tomorrow? A new era brings in a new life!