Header « Back to Glossary IndexA header is the extra information in a packet that is needed for the protocol stack to process the packet. Related Articles: Glossary: Cut-ThroughGlossary: Fragment Overlap AttackGlossary: FramesGlossary: Packet SniffingGlossary: Stateful InspectionHeader (Wikipedia)Look up header in Wiktionary, the free dictionary.Header may refer to: