Update

internet.md

@@ -76,7 +76,7 @@ Internet overtook the world thanks to having enabled great number of services to
 - **[intranet](intranet.md), [LAN](lan.md), [WAN](wan.md), ...**: Networks using basically the same technology as the Internet ([TCP](tcp.md)/[IP](ip.md), [ethernet](ethernet.md), [wifi](wifi.md), routers, ...), just on smaller scales -- the technology can actually be simpler: simpler routers can be used, no high performance backbone routers are needed, [Ronja](ronja.md) may be used instead of wifi, [DNS](dns.md) may be omitted and so on. There are many such networks, [military](military.md) has its own isolated networks, North Korea has its famous nation-wide isolated intranet ([Kwangmyong](kwangmyong.md)), Cuba has the famous [SNet](snet.md) -- "street net" that's used for pirating and games -- and so on. In Spain there is the famous [Guifi](guifi.md) network (with as of now nearly 40 thousand nodes) working in decentralized manner just on top of many interconnected wifi devices. The advantage is relative simplicity of implementation -- the technology is all there and quite cheap, you can set up your own network in the neighborhood and have complete control over it, government isn't gonna bully you for sharing movies, it won't spy on your communication (at least not so easily) etc.
 - **[radio](radio.md), [telegraph](telegraph.md)**: Plain FM/AM radio communication is a serious competition to Internet in terms of delay, bandwidth and distance of reach, while being very simple in comparison -- a skilled individual can construct or repair a radio with just some basic electronic components, which can't be said about digital computer networks that require extremely complex computer chips. Radio can relatively easily transfer analog information such as voice, but it can also send digital information. With [Morse code](morse_code.md) even the most primitive radio communication system can turn into something extremely powerful.
 - **[broadcast](broadcast.md) and alternative network topologies** (see also [world broadcast](world_broadcast.md)): broadcasts (one way communication towards many) can be implemented in many ways: with radio, audio, optically and so on. Broadcast only networks, such as [teletext](teletext.md), [TV](tv.md) or radio station broadcast, can be much simpler than a two way communication -- there don't have to be such complex protocols, there are no handshakes, devices can work on low power (as they're only receivers) and the broadcaster can't be overloaded by client requests. These can cover a great range of services such as news, weather forecast, time synchronization, geolocalization, work organization ("now we need you to produce this and this"), some forms of entertainment or providing generally useful data such as maps and books. If we do go for two way communication anyway, we should at least consider simpler network topologies -- with Internet we tend to think in mesh networks, i.e. "everyone connected to everyone", but that may be too complex to implement with other kinds of networks, it may be better to consider something like a ring network.
-- **optical telegraph, smoke signals, lanterns, flag semaphores, kites, flares, mirrors and other optical communication**: Optical communication is another technique widely used throughout history -- the advantage here is speed as obviously [light](light.md) is the fastest medium you can ever use. Lighting bonfires on hill tops could send a message about incoming enemy at great distances, later on even a more complex information could be sent using optical telegraph -- a chain of towers that forwarded symbols one to another by positioning big arms on their rooftops to form some specific shape, with the next tower copying the symbol and so on. You can leave big symbols in your window to send a few bytes to anyone with a telescope in the line of sight of your house. Basically if you can make someone see something, you can send a message; you can increase the amount of data by utilizing [color](color.md), movement, blinking and so on. Also remember that [optical fiber](optical_fiber.md) doesn't need a computer to work, it could probably be operated even manually provided we have some kind of [laser](laser.md).
+- **optical telegraph, smoke signals, lanterns, flag semaphores, kites, flares, mirrors and other optical communication**: Optical communication is another technique widely used throughout history -- the advantage here is speed as obviously [light](light.md) is the fastest medium you can ever use. Lighting bonfires on hill tops could send a message about incoming enemy at great distances, ancient Greeks could even send more complex messages this way (see Phryctoria), later on even a more complex information could be sent using optical telegraph -- a chain of towers that forwarded symbols one to another by positioning big arms on their rooftops to form some specific shape, with the next tower copying the symbol and so on. You can leave big symbols in your window to send a few bytes to anyone with a telescope in the line of sight of your house. Basically if you can make someone see something, you can send a message; you can increase the amount of data by utilizing [color](color.md), movement, blinking and so on. Also remember that [optical fiber](optical_fiber.md) doesn't need a computer to work, it could probably be operated even manually provided we have some kind of [laser](laser.md).
 - **[audio](audio.md) signals (bells, canon shots, drums, horns, megaphones, ...)**: Audio signal were again used a lot in history, a church bell could tell people many different things by how it was rang, canon shots could warn of incoming enemies and so on, voice can be used too. Drums are still widely used this way in Africa. The principle of string telephone can be considered to make some audio based networks.
 - **[pneumatic tube](pneumatic_tube.md)** and similar non-electric networks: A network of tubes using pressured air to transform small capsule containers from one place to another pretty fast, often used in factories -- this can carry written messages but also, unlike the Internet, physical objects! Other mechanism could be explored to construct similar networks, e.g. something based on hydraulics, string pulling, steam engines, gears, simple gravity (sending a marble down some tunnel could be a quite fast message) and so on.
 - **phone networks, [phreaking](phreaking.md), power line communication etc.**: phone networks (and possibly other networks like the electric network, TV network etc.) can be used for all kinds of communication, with [modems](modem.md) they can interconnect digital computers (which was widely used before Internet became widespread, see e.g. [BBS](bbs.md) networks); these networks can also be [hacked](hacking.md) to be used for free or cheap communication -- old time hackers knew how to rape phone boots to let them make free calls (see [phreaking](phreaking.md)). Networks primarily used for carrying power can also carry information alongside power (see [power line communication](plc.md)). Nowadays more anti hacking measures are in place but you may still e.g. exploit the fact that merely ringing someone's phone is completely free, which can be used to send a few [bits](bit.md) of information. WARNING: It's generally illegal to mess with these networks in unintended ways, trying this shit's always on you :-) Also touching random electric cables can kill you. If you by accident take down some optical cable or something, you'll be fined to death.