I do not understand how they are not the same thing? Is it that TCP/IP uses 803.11?
In: Technology
The Internet doesn’t use a single protocol. It uses a bunch of protocols, stacked up on top of one another, each of which does something different. These protocols are organized into layers.
The *physical layer* is basically a decision of how you’re going to connect two computers. Cat5 cable, radio waves, fiber optics, coaxial cable, infrared, and sometimes more exotic methods all fall into this category.
The *link layer* takes whatever physical layer you’ve decided upon, and organizes the actual way you send signals across that medium. 802.11 is an example of this: it tells two computers how to connect over radio waves in a particular frequency band, using agreed-upon signals inside that band. Another example is the Point-to-Point protocol, which is popular with landline phones. 802.3 is basically Ethernet.
The *network layer* (sometimes called the *internet layer*) handles the problem of getting a signal between two computers that aren’t connected, using a series of computers that are. This is where a lot of the magic in the Internet happens: because the link and network layers are separate, the computers in this chain don’t have to be connected the same way. A request to a given Website may go through differents kinds of cables, microwave or satellite uplinks, or possibly more exotic links before reaching the Website, and I don’t have to worry about the route it takes. IP (part of TCP/IP) lives in this layer, and it handles getting everything between different machines.
But that’s just for getting signals across. The *transport layer* is all about organizing those signals into meaningful data. TCP (another part of TCP/IP) lives here, and it deals with the logistics of making sure signals arrive in the right order, detecting if something goes wrong with a signal and re-sending it if needed, and other things. UDP is another popular protocol: it doesn’t handle all the reliability stuff that TCP does, but *because* it doesn’t try to do that, it can be faster than TCP in many circumstances, and that can be useful if you don’t need the connection to be rock-solid.
Lastly, there’s the *application layer*, which is all about what this data means. HTTP, which Websites use to communicate, lives here. So do the protocols used by E-mail. These protocols can be simpler, because they’re stacked on top of other protocols that handle the mundane aspects of running a network: HTTP doesn’t have to worry about how to connect to a machine halfway across the world, because IP already made that happen. And that’s how this layered model works.
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