The Skanda Purana (स्कन्दपुराण) is a massive Hindu scripture, famously known as the largest of the eighteen major Puranas. It is named after Lord Skanda (also known as Kartikeya or Murugan), the son of Shiva and Parvati and the commander of the celestial armies.
While it's named after Skanda, its primary focus is often the glorification of Lord Shiva and the sacred sites (Tirthas) associated with him.