In Jainism there are 24 Tirthankaras in the current cosmic half-cycle (avasarpini). Here’s the simple idea:

• The Jain cosmology describes many Tirthankaras across countless cycles. In the present half-cycle, 24 Tirthankaras appear in succession to restore and re-teach the path to Moksha.
• The sequence starts with Rishabhanatha (Adinath) and ends with Mahavira, who is the 24th Tirthankara of this cycle.
• The count of 24 is a traditional, canonical arrangement shared by the two main Jain sects (Digambar and Shwetambar). Some Jain texts may discuss earlier cycles with different numbers of Tirthankaras, but for this current cycle the accepted number is 24.
• The reason for this particular number is tied to the specific pattern of ethical decline, teaching, and revival that Jain scriptures describe for this era. Each Tirthankara promulgates the Dharma anew, reviving right belief, right knowledge, and right conduct, until the next Tirthankara appears.

If you’d like, I can summarize who each of the 24 Tirthankaras are and the key teaching each one is known for.