The vast majority of house wiring is insulated with PVC (polyvinyl chloride) — it is tough, flexible, moisture-resistant, a good electrical insulator and cost-effective. See what PVC insulation is for detail.
For safety, the PVC used in modern house wire is rarely plain. It is compounded into grades such as FR (flame retardant), FR-LS (flame retardant, low smoke) and HR-FR-LSH (heat resistant, flame retardant, low smoke & halogen) — each adding fire-safety performance, as compared in FR vs FR-LS vs HR-FR-LSH.
Premium wiring goes further, using cross-linked, halogen-free insulation such as XLPO / HFFR produced by e-beam cross-linking — see XLPE insulation. This offers higher heat resistance and longer life than standard PVC.
APAR offers the full spread: Shakti FR-PVC, low-smoke Anushakti HR-FR-LSH and Shakti FR-LSH, and the e-beam Fire Protekt (HFFR) wire. Compare them in the house wires and cables range.