Singh is not a Jain religious requirement or a fixed tradition. It appears as a surname for only some Jain families in certain regions, and its use varies by community and history.

• Meaning: Singh (lion) is a Sanskrit-derived title that has historically been used across many Indian communities as an honorific or clan name.
• Why some Jains use it: In some regions, Jain families adopted Singh due to cultural exchange with neighboring warrior or royal communities (like Rajputs or others) or as a mark of a former martial/warrior lineage, status, or respect shown by local rulers. It is a regional and historical happenstance rather than a doctrinal Jain practice.
• Who uses it: Not all Jains use Singh. Many Jains continue to use Jain, Shah, Oswal, Maheshwari, or other community-specific surnames depending on their lineage and region.

In short, the use of Singh among Jains is regional and historical, not a universal Jain tradition.