Where to Use Nmap

Hello community, i'm new here as you can see by the question.

I like practicing with Nmap but i don't want to cause problems for sysAdmins and i have no idea where to scan.

Is the any way to scan webservers or at least virtual and having my consciousness clear?

I enjoy all your tutorials and i see myself to continue with them, i only ask a way to practice not only Nmap but more kali stuff, without affecting other systems in the negative way.

Im using a LiveUSB kali (with persistence) , persistence partition is 10GB more or less, the whole USB is 16GB so no more space to allocation if needed.

Is it normal for the connection to fall while scaning (sending packets ) or at least slow it down?

Keep rocking.