Before we can venture into the world of web development, it's important to have a fundamental understanding of how the internet works. Meaning, what's happening behind the scenes when we type a web address into our web browser, or send a file or email to a recipient. This information will be very useful as we explore the concepts covered in this course.
To think of it in its simplest terms, the internet is a network of cables that facilitates the transmission of Data Packets.
This network is extremely vast, and spreads globally across 550,000 miles of hidden cables under the ocean, to keep the world connected.
This snapshot provides a graphical illustration of how complex the network of cables that power the internet, really is.
A data packet contains the information being transmitted (such as an email, file, or webpage) in raw text format, and also the location of the sender and recipient.
You can think of the location of a recipient or sender, as the physical address of your residence or a phone number. No two residences can have the same address and no two people have the same phone number. The same is true for internet addresses, also known as an IP Address.
An IP is a string of numbers separated by periods that identifies each computer that is connected to the internet. For example, the IP Address for google.com's web server is 18.104.22.168. Each website has its own unique IP Address. We will discuss how this IP translates into google.com later in this lesson.
Let's take a look at an example of an email Data Packet.
This data packet consist of three parts.
The speed at which these data packets can be transmitted over a network is determined by bandwidth.
Bandwidth transmission capacity is measured by bitrate. The bitrate is the number of bits per second that a digital network can transmit. Another measure of data transmission speed is Latency. This is the amount of time it takes for 1 bit to be sent from the sender to the receiver.
Let's say you want to send a 4MB mp3 file to a friend through an email attachment, in 4 seconds. Since 8 Million bits = 1MB, you would require a bit rate of 8 Mbps.
With billions of people connected to the internet at any given moment, it goes without saying that the internet is comprised of hundreds of thousands of networks and links billions of devices together, globally. With this level of connectivity, you might be wondering how each individual network device can efficiently and accurately interpret data packets from various unique senders.
Well, you can think of the internet as an architecture expressed in a set of protocols. A protocol is a well-established set of rules and standards used to communicate between machines. We have already touched on one protocol, the IP Protocol.
The IP Protocol is used to route information to the proper address and make sure the data packets are sent to the intended recipient. Note that the IP Protocol does not facilitate physical connections between computers to transmit data packets.
The TCP protocol is intended for that purpose. The TCP protocol makes sure that transmitted data packets are received without any missing information. If it is determined the data packet(s) are missing data, TCP will request that the sender resends them.
Some other protocols that we will explore in this course include HTTP, HTTPS, SMTP and FTP.