Communication on the internet is not just data being sent. It works because the sending side and receiving side exchange data according to the same rules.
These communication rules are called protocols.
When you view a website, send email, or an app communicates with a server, various protocols are used behind the scenes. HTTP, DNS, TCP, UDP, and TLS are protocols with different roles.
For beginners, they may look like separate technical terms. In practice, however, they are all "rules for making communication work."
This article does not go deeply into protocol details. Instead, it organizes what role each one has in communication.
Protocols Are Communication Rules
A protocol is a set of rules for communication.
In communication, the following kinds of things need to be decided in advance.
What format to use when sending data
In what order exchanges should happen
How to specify the other party
How to confirm that data arrived
Whether to encrypt communication content
How to handle errors when they occur
If the sending side and receiving side operate by different rules, communication cannot work. Even if data is sent, the receiving side cannot understand what it means.
In other words, protocols are common rules that allow computers to communicate correctly with each other.
Why Communication Needs Agreements
On the internet, many different devices around the world communicate with each other.
Many devices and pieces of software are involved, including PCs, smartphones, servers, routers, DNS servers, apps, and browsers. If each one communicated in its own way, data could not be sent or received correctly.
So common rules are defined for each type of communication. By following those rules, devices from different manufacturers and different operating systems can access the same website.
Because protocols exist, many kinds of devices on the internet can communicate inside the same mechanisms.
Common Protocols Used on the Web
When accessing a website, multiple protocols and mechanisms are involved.
Representative examples include the following.
Protocol or mechanism
Main role
DNS
Looks up the IP address corresponding to a domain name
HTTP
Exchanges web page data
HTTPS
Protects HTTP communication with TLS
TCP
Delivers data accurately
UDP
Sends data with emphasis on speed and real-time behavior
TLS
Encrypts communication content
They do not all have the same role. They are responsible for different ranges within communication.
The Role of DNS
DNS is a mechanism for looking up the IP address corresponding to a domain name.
When accessing a website, you normally do not enter an IP address directly. For example, you use a domain name such as example.com.
However, for a computer to actually send data to the communication destination, an IP address is needed. So DNS is used to look up the IP address corresponding to the domain name.
In other words, DNS is a mechanism for looking up the IP address of the party you want to communicate with.
Traditional DNS queries may be sent without encryption. In that case, which domain name was looked up may be visible on the network.
The Roles of HTTP and HTTPS
HTTP is a protocol for exchanging web page data.
It is used when a browser requests "please show me this page" from a web server, and the server returns data such as HTML, images, CSS, and JavaScript.
HTTPS is a mechanism that protects HTTP communication with TLS. By encrypting the content exchanged over HTTP with TLS, it makes the content harder to read from the communication path.
With HTTP alone, communication content is not encrypted. With HTTPS, on the other hand, communication content is encrypted, so it becomes harder for an intermediate network to read the content as-is.
However, even when HTTPS is used, not all information related to the communication is hidden. The destination IP address, traffic volume, connection timing, and similar information may be visible in other forms.
The Roles of TCP and UDP
TCP and UDP are protocols related to how data is delivered.
TCP emphasizes delivering data accurately. It has mechanisms for resending data if it drops out along the way and for arranging data into the correct order.
It is often used for communication where accuracy is important, such as website browsing, email, and file transfer. Today, there are also web communication mechanisms such as HTTP/3 that use UDP.
UDP, on the other hand, emphasizes speed and lightness. Because it does not perform detailed delivery confirmation like TCP, it has characteristics that make communication latency easier to reduce.
UDP may be used for communication where low latency matters, such as voice calls, video calls, online games, and DNS.
TCP and UDP are not ranked above or below each other. TCP is used for communication that emphasizes accuracy, and UDP is used for communication that emphasizes speed and real-time behavior.
The Role of TLS
TLS is a protocol for encrypting communication content.
When accessing a website over HTTPS, TLS is what actually handles protection of the communication content. TLS encrypts the content exchanged between the browser and the server.
For example, login information, search content, and content entered into forms become harder to read on the communication path because of HTTPS.
TLS is related not only to encryption, but also to verification of the communication partner and detection of tampering. However, for this article, it is enough to first understand it as "a mechanism for protecting communication content."
Also, TLS is a mechanism for protecting communication content. It does not completely hide the existence of the communication itself. Information such as which server you are communicating with, when you communicated, and how much data was communicated may be visible in other forms.
One Communication Uses Multiple Protocols
Communication for accessing a website does not use only one protocol.
For example, when opening a website in a browser, the rough flow is as follows.
Use DNS to look up the IP address corresponding to the domain name
Use TCP, UDP, or similar mechanisms to handle characteristics related to how data is delivered
Use TLS to protect communication content
Use HTTP to exchange web page data
Actual communication has more detailed processing. However, the important point is that multiple protocols share roles.
DNS has the role of looking up the destination IP address. TCP and UDP have the role of deciding how data is delivered. TLS has the role of protecting communication content. HTTP has the role of exchanging web page information.
In this way, even a single web access combines multiple protocols.
Each Protocol Protects a Different Scope
When understanding protocols, it is important to think separately about the scope each one is responsible for.
For example, using HTTPS does not mean all information related to communication is hidden. HTTPS mainly protects the content exchanged between the browser and web server.
However, the destination IP address, DNS queries, traffic volume, connection timing, and similar information may be visible from other perspectives.
Also, traditional DNS queries may be sent without encryption. In that case, which domain name was looked up may be visible on the network.
In this way, it is important to understand what a given protocol protects and what it does not protect.
An Important Perspective for Thinking About Anonymity
When thinking about anonymity, understanding protocols is very important.
That is because the information that is visible and the scope that is protected change depending on which protocol is being used.
For example, if HTTPS is used, the content of a web page is encrypted. However, the destination IP address and communication timing are not completely hidden.
If you understand how DNS works, you can see that a domain-name query happens before accessing a website. If you understand the difference between TCP and UDP, it becomes easier to organize communication characteristics and where they are used. If you understand the role of TLS, you can separate the scope that is encrypted from information that may not be encrypted.
To improve anonymity, it is not enough to look only at "whether it is encrypted." You need to think separately, protocol by protocol, about which parts of the communication are visible and which parts are protected.
Summary
A protocol is an agreement for making communication work.
When the sending side and receiving side follow the same rules, computers can exchange data correctly with each other.
In web communication, multiple protocols and mechanisms are involved, including DNS, HTTP, HTTPS, TCP, UDP, and TLS. Each one has a different role within communication.
DNS looks up the IP address corresponding to a domain name. HTTP exchanges web page data. HTTPS protects HTTP communication with TLS. TCP delivers data with an emphasis on accuracy. UDP sends data with an emphasis on speed and real-time behavior. TLS protects communication content.
Even one communication combines multiple protocols.
When thinking about anonymity, it is important to understand which protocol protects what and what it leaves visible. When you understand the differences between protocols, it becomes easier to organize which parts of communication are protected and where information may remain.
Related tools
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An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.