The main actors of the web: browser, server, search engine, and content provider
Objectives
By the end of the lesson, you can list who takes part in creating, delivering, finding, and using a web page, and you can say which actor is responsible for what.
Why is "browser and server" not enough?
When we open a news page, we type a single address, yet a chain of actors works in the background. The browser asks for name resolution and establishes a connection, it may download the images from another geographic location, a search engine may have crawled the page earlier, and the provider may also use an external analytics or payment system. If we see only two actors, we do not understand where something can go wrong and who is responsible for it. This is why it is worth looking at the web as an ecosystem.
User and browser
The browser is the program that communicates with the web service on the user's behalf. It does not merely display pages: it sends network requests, checks security certificates, processes documents, stores certain data, and, following its own security rules, limits what web pages may do. This is why it is also called a user agent: the user's representative.
Examples: Chrome, Firefox, Safari, Edge. They support common standards but can differ in the details, which is why interoperability matters (1.5).
Web server, application, and data store
A web server receives HTTP requests and sends responses. In a simple case it returns a file: an HTML page, an image. In a more complex service the request reaches an application, which can fetch data, check authorization, and produce the response from the result.
The roles do not always have to be separated sharply, but it is worth knowing them:
- the web server receives web traffic and can forward it;
- the application implements the rules of the service (its business logic);
- the data store (for example a database) keeps the data and makes it queryable.
Content provider
The content provider is the organization or person responsible for the information or service available on the web: a university, a news portal, a company, a private person, a public institution. They do not necessarily operate the server: the hosting, delivery, or protection can also be provided by an external company.
This distinction matters for questions of responsibility. The content provider is typically responsible for the content, the data handling, and the terms of the service; part of the infrastructure is operated by others.
Search engines
A search engine helps people find content. Automated programs (robots, crawlers) walk through public pages, follow links, and build an index. When someone searches, the search engine picks and ranks results from this index.
A search engine is not the web, and it does not guarantee that it knows every page. Whether a page can be found depends on the structure of the content, the access rules, the links, and the search engine's own ranking principles. The search engine only provides the result; when the page is used, the browser already turns directly to the provider.
sequenceDiagram
actor F as User
participant K as Search engine
participant B as Browser
participant S as Web service
F->>K: Search
K-->>F: Results (addresses)
F->>B: Open a result
B->>S: Request
S-->>B: Response
B-->>F: Display the page
When a page is opened, further actors take part, often unnoticed:
| Actor |
What does it do? |
| Internet service provider |
Provides network connectivity |
| Domain registrar |
Manages the registration of the domain name |
| DNS provider |
Assigns an IP address to the name |
| CDN (Content Delivery Network) |
Delivers content from several geographic locations |
| Certificate authority (CA) |
Issues certificates for HTTPS |
| External login provider |
Provides a central authentication service |
| Advertising, analytics, and payment provider |
Adds a separate function to the page |
Chapters 4 and 7 discuss their details; here it is enough to know that they exist, and that each one means a new dependency, a new area of responsibility, and a new possible point of failure.
Worked example: the actors of Kurzuspont
| Actor |
Role in Kurzuspont |
| Student and their browser |
Searching for courses, enrolling |
| Kurzuspont application |
Course list, enrolment rules, permissions |
| Database |
Courses, enrolments, users |
| University authentication service |
Authenticating the student (chapter 7) |
| Email service |
Sending confirmations |
| CDN |
Fast delivery of static files (chapter 4) |
| Search engine |
Making public course descriptions findable |
If a student experiences an enrolment error, the cause can be any of the actors: the browser, the network, the application, the database, or the external authentication service. This is why you need to know the actors, both for troubleshooting and for sharing responsibility.
Common misconceptions
| Statement |
Clarification |
| "A server is a single physical computer." |
A server is a role: it can be a virtual machine, a group of machines, or a cloud service. |
| "A search engine creates web pages." |
A search engine finds and ranks content published by others. |
| "The hosting provider is responsible for everything on the site." |
The content provider is typically responsible for the content, the data handling, and the terms of the service. |
| "The browser just displays the page." |
The browser sends requests, enforces protection rules, and stores data. |
In brief
- On the web, the user, the browser, the server, the application, the data store, the content provider, the search engine, and several supporting providers work together.
- The browser is the user's representative (user agent), not just a viewer.
- The content provider is responsible for the content and the data handling, even if someone else operates the infrastructure.
- A search engine helps with finding content; it does not create it, and it does not know every page.
Review questions
- List who takes part in opening the page of a web shop!
- What is the difference between the role of the web server and that of the application?
- Why is the content provider not necessarily the same as the operator of the server?
- How does a search engine build an index?
Learning resources
The main actors of the web: browser, server, search engine, and content provider
Objectives
By the end of the lesson, you can list who takes part in creating, delivering, finding, and using a web page, and you can say which actor is responsible for what.
Why is "browser and server" not enough?
When we open a news page, we type a single address, yet a chain of actors works in the background. The browser asks for name resolution and establishes a connection, it may download the images from another geographic location, a search engine may have crawled the page earlier, and the provider may also use an external analytics or payment system. If we see only two actors, we do not understand where something can go wrong and who is responsible for it. This is why it is worth looking at the web as an ecosystem.
User and browser
The browser is the program that communicates with the web service on the user's behalf. It does not merely display pages: it sends network requests, checks security certificates, processes documents, stores certain data, and, following its own security rules, limits what web pages may do. This is why it is also called a user agent: the user's representative.
Examples: Chrome, Firefox, Safari, Edge. They support common standards but can differ in the details, which is why interoperability matters (1.5).
Web server, application, and data store
A web server receives HTTP requests and sends responses. In a simple case it returns a file: an HTML page, an image. In a more complex service the request reaches an application, which can fetch data, check authorization, and produce the response from the result.
The roles do not always have to be separated sharply, but it is worth knowing them:
Content provider
The content provider is the organization or person responsible for the information or service available on the web: a university, a news portal, a company, a private person, a public institution. They do not necessarily operate the server: the hosting, delivery, or protection can also be provided by an external company.
This distinction matters for questions of responsibility. The content provider is typically responsible for the content, the data handling, and the terms of the service; part of the infrastructure is operated by others.
Search engines
A search engine helps people find content. Automated programs (robots, crawlers) walk through public pages, follow links, and build an index. When someone searches, the search engine picks and ranks results from this index.
A search engine is not the web, and it does not guarantee that it knows every page. Whether a page can be found depends on the structure of the content, the access rules, the links, and the search engine's own ranking principles. The search engine only provides the result; when the page is used, the browser already turns directly to the provider.
sequenceDiagram actor F as User participant K as Search engine participant B as Browser participant S as Web service F->>K: Search K-->>F: Results (addresses) F->>B: Open a result B->>S: Request S-->>B: Response B-->>F: Display the pageIntermediary and supporting actors
When a page is opened, further actors take part, often unnoticed:
Chapters 4 and 7 discuss their details; here it is enough to know that they exist, and that each one means a new dependency, a new area of responsibility, and a new possible point of failure.
Worked example: the actors of Kurzuspont
If a student experiences an enrolment error, the cause can be any of the actors: the browser, the network, the application, the database, or the external authentication service. This is why you need to know the actors, both for troubleshooting and for sharing responsibility.
Common misconceptions
In brief
Review questions
Learning resources