The task of a lightning protection system is to protect a building and the people in it from lightning effects. In addition, a modern lightning protection system also protects the technology from overvoltages. It consists of

• External lightning protection
  External lightning protection protects a building by the arresting devices absorbing direct lightning strikes and introducing the lightning current via the conductors (not to be confused with lightning arresters) into the earthing system in the ground. External lightning protection does not prevent the lightning from hitting the building, but offers the lightning a metal connection at the preferred points of impact, which is able to transport the lightning current towards the earth permanently and without danger to people and the object to be protected. This prevents direct lightning strikes into people.
• Internal lightning protection
  An essential component is lightning protection equipotential bonding. All metal pipe installations and all cable installations (electricity, DSL, cable TV, SATTV, etc.) are connected to each other and to the main grounding rail, if necessary with SPDs type 1. This prevents voltage differences and the associated lightning flashovers in the building with subsequent fire and personal hazard. This lightning protection equipotential bonding goes beyond protective equipotential bonding according to DIN VDE 0100-410 and DIN VDE 0100-540 (surge protection).
• Überspannungsschutz
  Wenn der Innere Blitzschutz auch einen Schutz der Kabel-Installationen und der daran
  angeschlossenen Geräte übernehmen soll, spricht man vom Überspannungsschutz. Durch
  Überspannungsschutzgeräte (SPDs Typ 2) in den Verteilern für die Energietechnik und den
  Übergabe- und/oder Speisepunkten der informationstechnischen Systeme wird die
  auftretende Überspannung auf ein für die Endgeräte ungefährliche Werte begrenzt. Bei
  Leitungslängen größer etwa 5 m sind weitere Ableiter (SPDs Typ 3) unmittelbar am
  Endgerät für einen vollständigen Schutz erforderlich.

Surge protection can therefore be seen as part of lightning protection, but it can also be set up independently as basic protection for electrical installations and personal protection.