If two people are conversing in a crowded room, that conversation is vulnerable to eavesdropping. However, if they are conversing in a language the eavesdropper doesn't understand, the conversation is effectively private. Similarly, two electronic devices communicating over public wi-fi could be vulnerable to eavesdropping. However, if the electronic conversation uses a VPN (Virtual Private Network), the effect is similar to people conversing in a foreign language; the eavesdroppers won't understand a word.
Any web site that you visit whose URL starts with "https/" is already secure. All your other internet communication is not secure. Think about the non "https" web sites you visit, the emails you send and receive, and the files you store in cloud storage (One Drive, Google Drive, Dropbox, etc). All this communication between your computer and a non "https//" web site that occurs on public wi-fi is potentially vulnerable to eavesdroppers. If you use a VPN, the midpoint of your electronic conversation will shift from the server of the network provider you are on to the server of your VPN service, and the conversation will take place over an encrypted tunnel that is not subject to eavesdropping. Therefore, all communication (not just "https") will be secure.
Additional benefits of a VPN are: Your location will be hidden - the target web site will believe your location to be the location of the VPN server; Your service provider will not see the websites to which you navigate - therefore they can't track your browsing history to sell for additional revenue.
There are many VPN services to choose from. Before signing up, read the reviews. The criteria to look for should be price, little to no decrease in internet speed, and whether or not the VPN logs your browsing history. Some VPN services are free, but before signing up, find out if their business model might be detrimental to you; Do they sell log and sell your browsing history? Free is not necessarily better. Some subscription services to check out are ExpressVPN, NordVPN, and Surfshark.
You may have heard of the TOR network, which is another secure way to browse the web. However TOR emphases anonymity for those folks wanting to browse the dark web, whereas, VPN emphases privacy for those of us that simply want to protect our data and identity.
