Absolute URLs are used to represent all the contents needed for a specific file in the Internet. Each file in the Internet has a unique URL, which is the connection you need to enter into the address bar when searching on a web page.
For example, if you want to enter a web page on Baidu, enter: http://www.baidu.com./ in the web address bar.
Once you enter a certain web page, the link to the observation address bar may become very long when clicking on other screens inside it, because the address of the clicked content will be used: relative URL. The relative URL is only suitable for other directories under the links of the web page of the same name, and it will be invalid if you enter other websites. If you want to connect to a resource in the same directory, you only need to change the file name, and the original address does not need to be replaced.
1. Subdirectory
The subdirectories in the computer are easy to understand. For example: C:/ is the parent directory, C:/Windows is the subdirectory of C:/; C:/Windows/System32/ is the subdirectory of C:/Windows.
Each level of subdirectories only needs to add slashes/and then add file names to form a subdirectories.
2. Parent directory
Parent directory: that is, C:/Windows/System32/ in the same 1, C:/Windows is the parent directory of System32.
3. Root directory
Root directory: The example is the same as above, that is, C:/ is the root directory.
This is true for directories in html. But the root directory needs to be replaced with this mode: architecture + server address + file name.
Example:
http://www.wrox.com/index.html;