Aside from being at home and using your home internet network to get online (which should be encrypted for your online safety and to keep everyone in the neighborhood from using it), most people don't give much thought to the safety of using other networks when they are not at home. In a coffee shop with free wifi? Great just log in! At a hotel that offers free wifi? Great just get the user code (usually your room number) and log in! In a mall with free wifi and waiting for the spouse to finish shopping? Great just log in!
The only problem with just logging into a free wifi network is that your information can get jacked, your secure passwords can be compromised, and the credit card you are using to purchase something online with can get hijacked and used by people who specialize in this sort of theft. Yikes.
If you tend to use the internet while in public places, you can protect yourself by using a virtual private network (VPN). I highly recommend using a subscription type VPN service instead of a "free" service since nothing is ever really free. You can do a bit of Googling to find the best VPN service for your needs. Once you have decided on a VPN service be sure to check TechBargains and see if there are any discount codes to be had for your service of choice.
Remember, a VPN service is a better way to protect your online activities than doing nothing BUT your security can still be compromised by several other things including theft of your cell phone or laptop, video surveillance at the public location you are at (ie: video cameras in a coffee shop installed by the business for general security but which can record everything you are doing on your laptop), power surges if you are plugged into an outlet, other customers looking over your shoulder and recording what you are doing on their cell phone, data theft (always require a password to access your home screen), etc.