Disable Gatekeeper in macOS High Sierra, open unidentified and "damaged" apps.

Sometimes you want to install some app from the internet, and your Mac gives you an error that says something like "can't be opened because it's from an unidentified developer" or "...is damaged and can't be opened. You should move it to the Trash."

Well if you trust the app, and want to install it anyways. Just disable macOS Gatekeeper.

• Open the terminal in your utilities folder. 
• enter the code: sudo spctl --master-disable
• Enter your password
• Open your app.

You're welcome. 
Re-enable gatekeeper with: sudo spctl --master-enable