When a packet is sent across several networks, each router forwards it onward. The Web layers its design so that the routers and modems between a browser and a server stay hidden below the HTTP messages.
Big networks on the internet are called autonomous systems. Each one is a set of routers under a single technical administration. Neighbouring networks use the Border Gateway Protocol, BGP, to swap network reachability information, which tells each network which destinations it can reach through its neighbours.
Internet exchange points are places where internet service providers swap data directly with each other, on switches that connect the networks taking part. Swapping traffic there means an ISP sends less of its traffic through upstream transit providers, which lowers the cost of carrying each bit. By May 2013, researchers counted more than 300 exchange points working around the world.
A website's digital certificate ties its domain name to its keys, so the browser knows it is really connected to that site.
The first request to a website takes longer because it includes a DNS lookup, a TCP handshake and the secure TLS negotiation, while later requests reuse the connection.
As of November 2026, the U.S. Department of Energy says data centers use 10 to 50 times as much energy per floor area as a typical commercial office building.
In 1945, Vannevar Bush described a device called a Memex that could follow links between documents, an early idea behind hypertext. Between 1962 and 1963, J. C. R. Licklider wrote memos that imagined an "Intergalactic Computer Network" where anyone could quickly reach information on any subject.
On October 29, 1969, a computer at UCLA made the first connection to a computer at the Stanford Research Institute, and the first log-in attempt crashed the far computer before the next try worked. The National Science Foundation launched NSFNET in 1986, and it grew from about 2,000 connected computers in 1986 to more than 2 million by 1993.
The first Web proposal was written in March 1989, and a formal proposal was made with Robert Cailliau in November 1990. The first web server's computer had a hand-written label in red ink: "This machine is a server. DO NOT POWER IT DOWN!!"
In 2025, about 6 billion people, about three-quarters of the world, were using the internet, and about 2.2 billion were not, according to ITU. In ITU's 2025 data, 94 percent of people in high-income countries used the internet, compared with 23 percent in low-income countries.
Few ships can repair undersea cables, so a repair can wait for one to become free, and in early 2025 an expert said that about 60 to 70 ships worldwide could in theory do repairs, but most are cable layers, and only around 25 to 30 are special ships for repair and maintenance. Cable owners often pay a yearly fee to share repair ships.
As of early 2025, a repair itself takes about one to two days, mostly for splicing the glass fibers, not counting the ship's trip to the site, but the whole job can take far longer: ITU says repair delays can last weeks or months, and one expert says some countries take an average of six weeks to approve a repair.
Companies spread their traffic across several cables, so if one breaks the network keeps running over the others while the broken one is repaired. As of November 2026, almost all the data that travels between countries goes through cables laid on the sea floor.
Words to know
- autonomous: self-governing
- certificate: proof of identity
- handshake: connection setup
- hypertext: linked text
- exchange: swapping place
