When trying to call /dev/tcp/www.google.com/80, by typing

/dev/tcp/www.google.com/80 

Bash says no such file or directory. When looking at other people's code online, they use syntax such as

 3<>/dev/tcp/www.google.com/80 

I noticed that this works as well:

</dev/tcp/www.google.com/80

Why are these symbols required to call certain things in bash?