Server blocks

One nginx can serve many different websites. The piece that describes a single website is called a server block, and it is the first thing you write for any site. This lesson shows what an nginx server block is and how to write the smallest useful one.

What is an nginx server block?

A server block is a server { } section in your config. It tells nginx: "when a request comes in that matches this, here is how to answer it."

In the Apache world the same idea is called a virtual host. Nginx calls it a server block, but it means the same thing: one config for one site, and you can have many of them side by side.

You met contexts and directives in Directives and contexts. A server block is a context. It lives inside the http block and holds directives that describe one site.

A minimal server block

Here is about the smallest server block that does something real:

server {
    listen 80;
    server_name example.com;
    root /var/www/example;
}

Three lines, three jobs:

• listen 80; - answer requests on port 80 (plain HTTP).
• server_name example.com; - this block is for the domain example.com.
• root /var/www/example; - the files for this site live in this folder.

Do not worry about the exact meaning of each one yet. The next three lessons cover listen and server_name, then root and index, one at a time.

Where the block lives

A server block does not float on its own. It sits inside the http context:

http {
    server {
        listen 80;
        server_name example.com;
        root /var/www/example;
    }
}

In a real install you rarely edit the big http block by hand. As you saw in Includes and sites, each site usually gets its own file in conf.d/ or sites-available/, and nginx pulls them all in with include. Each of those files holds one server block.

Run many sites from one nginx

You can add a second server block for a second site:

server {
    listen 80;
    server_name example.com;
    root /var/www/example;
}

server {
    listen 80;
    server_name blog.example.com;
    root /var/www/blog;
}

Both listen on port 80. Nginx picks the right one using the server_name, which is the topic of the next lesson.

One thing to watch: if two blocks accidentally carry the same server_name, nginx still starts, but it prints a conflicting server name warning and quietly uses the first block it read. The site loads, so the bug hides until you notice the wrong page is answering.

Common mistake

Forgetting that a server block must sit inside http. If you paste a bare server { } at the very top of nginx.conf, nginx refuses to load. Run nginx -t after every edit, as covered in Testing config safely. It catches this in a second and prints the exact line.

FAQ

Is "server block" the same as "virtual host"?

Yes. Apache says virtual host, nginx says server block. Same concept: one config for one site.

How many server blocks can I have?

As many as you need. One nginx routinely serves dozens of sites, each in its own server block.

Do I need one file per server block?

No, but it is the common habit. One file per site in sites-available/ keeps things tidy and easy to enable or disable.