That value is the id of the next protocol header right after Ethernet. The Ip4 header has a reserved id value of 0x800 for it. So anyone reading that packet has to look into that type field in order to determine the next protocol. When he does, 0x800 in that field tells him the next header is Ip4.
1 The Constitution contains no reference to any right to privacy. 2  However, over more than 100 years, courts have found a fundamental (but somewhat vague) right to privacy implicit in the Constitution.
This story first appeared on the TomDispatch website. Here's a bit of history from another America: the Bill of Rights was designed to protect the people from their government. If the First Amendment's right to speak out publicly was the people's wall of security, then the Fourth Amendment's right to privacy was its buttress. It was once thought that the government should neither be able to stop citizens from speaking nor peer into their lives.