Origin story
When Brahma's fifth head grew arrogant, Shiva cut it off and was afflicted with the sin of Brahmanahatya. He wandered as Bhairava until the sin was released in Kashi, where he became the city's guardian, Kalabhairava.
The trishula, the skull and the dog express the destruction of ego and the guarding of boundaries. Bhairava is the protector who confronts fear directly, and his shrines stand at the threshold of temples and villages, where he watches over the sacred space.
Source: Wikipedia: Bhairava — https://en.wikipedia.org/wiki/Bhairava
Symbolism
The trishula, the skull and the dog express the destruction of ego and the guarding of boundaries. Bhairava is the protector who confronts fear directly.
Sloka
1
Kalabhairava Ashtakam (First Verse)
देवराजसेव्यमानपावनाङ्घ्रिपङ्कजं व्यालयज्ञसूत्रमिन्दुशेखरं कृपाकरम्। नारदादियोगिवृन्दवन्दितं दिगम्बरं काशिकापुराधिनाथकालभैरवं भजे॥
Devarāja Sevyamāna Pāvanāṅghri Paṅkajaṃ Vyāla Yajña Sūtram Indu Śekharaṃ Kṛpākaram, Nāradādi Yogivṛnda Vanditaṃ Digambaraṃ Kāśikāpurādhinātha Kālabhairavaṃ Bhaje
Meaning — I worship Kalabhairava, the lord of Kashi, whose sacred lotus feet are served by the king of the gods, who wears a serpent as his sacred thread and the moon as his crest, the compassionate one, saluted by Narada and the assembly of yogis, the sky-clad guardian.
Recited for: Dhyana and protection
