Why 24? In Jain cosmology, time is cyclical. In each half-cycle (avasarpini) or period of time when the world evolves and then declines, a set of perfected teachers called Tirthankaras appears to teach the righteous path anew. The tradition counts 24 such Tirthankaras who revive and restore Jain dharma in different ages. In the present half-cycle, Mahavira is considered the 24th Tirthankara.
What is a Tirthankar? A Tirthankar is a liberated soul (a perfected, omniscient teacher) who shows the path to Moksha (liberation) and establishes the fourfold order (monks, nuns, laymen, laywomen). After teaching and guiding beings, they pass away at the end of their era and a new Tirthankar appears in a future, different era.
Is there any difference between Digambar and Shwetambar? Both traditions recognize the same sequence of 24 Tirthankaras for the current half-cycle and typically name similar figures (e.g., Rishabhanatha, Ajitnath, Sambhavnath, …, Parshvanath, Mahavira). There can be minor variations in the order or in some regional recounting, but the overall concept and the count (24) remain widely accepted across both streams. If you’re looking for a precise list in a specific tradition, I can lay out the names as they appear in that tradition.
If you want, I can give you the conventional list of the 24 Tirthankaras or explain how their teachings are believed to revive dharma in each era.