What is the difference between a domain name and a URL?

The terms "domain name" and "URL" (Uniform Resource Locator) are related concepts used to identify and locate resources on the internet, but they serve different purposes and represent different aspects of web addressing:

### Domain Name:

- **Definition:** A domain name is a human-readable label used to identify a specific location on the internet. It is part of the hierarchical Domain Name System (DNS) and typically consists of two main parts:
  - **Second-Level Domain:** The primary name of the website (e.g., example in example.com).
  - **Top-Level Domain (TLD):** The domain's suffix that indicates the type or purpose of the domain (e.g., .com, .org, .net).

- **Purpose:** Domain names are used to provide a memorable and recognizable name that represents a specific website or web service. They are easier to remember than IP addresses and serve as the primary means for users to access websites.

- **Example:** In the domain name "example.com":
  - "example" is the second-level domain.
  - ".com" is the top-level domain.

### URL (Uniform Resource Locator):

- **Definition:** A URL is a specific type of Uniform Resource Identifier (URI) that provides the exact location of a resource on the internet and specifies how to access it. A URL includes several components that together define the path to a particular resource:

  ```
  scheme://host:port/path?query#fragment
  ```

  - **Scheme:** Specifies the protocol used to access the resource (e.g., http://, https://, ftp://).
  - **Host:** The domain name or IP address where the resource resides (e.g., www.example.com).
  - **Port:** Optional; specifies the port number to connect to the host (e.g., :80 for HTTP).
  - **Path:** The specific location of the resource on the server's file system (e.g., /path/to/resource).
  - **Query:** Optional; parameters passed to the resource (e.g., ?key1=value1&key2=value2).
  - **Fragment:** Optional; identifies a specific section within the resource (e.g., #section).

- **Purpose:** URLs are used by web browsers and other applications to locate and access resources such as web pages, files, images, APIs, and more on the internet. They provide a precise address that directs browsers to retrieve and display the requested content.

- **Example:** In the URL "https://www.example.com/index.html":
  - "https://" is the scheme (protocol).
  - "www.example.com" is the host (domain name).
  - "/index.html" is the path to the specific resource (web page).

### Key Differences:

1. **Nature:**
   - **Domain Name:** A domain name is a broader identifier that represents a website or online service, typically consisting of a second-level domain and a top-level domain.
   - **URL:** A URL is a complete address that specifies the exact location of a resource on the internet, including the protocol, domain name, path, and other optional components.

2. **Components:**
   - **Domain Name:** Consists of a second-level domain and a top-level domain (e.g., example.com).
   - **URL:** Includes the scheme (protocol), host (domain name or IP address), path, query parameters, and fragment identifier.

3. **Usage:**
   - **Domain Name:** Used primarily to identify and access websites and services in a human-readable format.
   - **URL:** Used by browsers and applications to retrieve specific resources from servers based on the provided address.

In summary, while domain names and URLs are related concepts used to identify resources on the internet, a domain name is a part of a URL and serves as a human-readable identifier for websites, whereas a URL is a complete address that specifies the location and access method for a particular resource on the web.