Can I edit hosts without sudo?

You can, but it's a bad idea. The whole point of the permissions system is preventing non-privileged users and attackers from doing stuff like writing to system files, running hostile code, and so on. By far the best thing to do is just keep on using sudo when you need to edit system files. That's best practice and it's the reason we have sudo

I don't recommend either of the following methods, but they are safer than the dreaded chmod 777. You could, for example, change the group ownership of /etc/hosts and give the group write permission:

sudo addgroup editors            #make a new group
sudo adduser $USER editors       #add yourself to it
sudo chown :editors /etc/hosts   #change the group ownership
sudo chmod 664 /etc/hosts        #give the group write permission

You would now be able to edit the file without sudo. Or, you could use ACLs, if you have the acl package (installed for sure in 15.04 and later)

sudo setfacl -m $USER:rw /etc/hosts

But, again, I don't recommend either of those actions. Just use sudo.

I wouldn't adjust the permissions of any system related file

What you can do is make a basic script

#!/bin/bash
sudo nano /etc/hosts

Call it whatever you want, for example, edithosts.sh and put it in a scripts folder inside your home folder.

chmod 700 /path/to/script/file/edithosts.sh This will prevent unauthorised reading or writing to the file because ss TripeHound said, the contents of this file are now run with root permissions with no password.

Then add the following line to /etc/sudoers

tom ALL = (root) NOPASSWD: /path/to/script/file/edithosts.sh 

That will allow you to sudo sh /path/to/script/file/edithosts.sh without having to enter a password

Recommended solution

As @paul pointed out in the comments, sudoedit could be a better solution.

tom ALL = (root) NOPASSWD: sudoedit /etc/hosts

Because this solely allows editing of /etc/hosts and doesn't leave you running an elevated text editor