VPN(Virtual Private Network)

Advantages:

Fast
Secure
Don't save logs
Guaranteed anonymity
Can be set up for all applications on various devices like laptops, cell phones, tablets, etc.

Working:

Creates virtual tunnel between client(you) and server accessed and all conversions that pass through are encrypted(regardless of protocols)

Advantages:

Used by large scale businesses to allow employees to access internal network in a secure way
To hide one's IP from hackers, snoopers, government, ISPs, etc.
Used to bypass restrictions placed by colleges, schools, offices, etc.
To avoid region wide block of some IPs

Commonly used:

HotspotShield
ExpressVPN
hide.me

Disadvantage:

Makes hackers untraceable by Police or other authorities