pros = much more private than any other method, except TOR
usually encrypted (I think)

cons = yes, you have to pay per month or quarter for a good VPN (the free ones make you the product somehow)
I am not 100% sure the NSA cannot hack them

Who needs it ? Anyone who strongly values their privacy

might come in handy to avoid tracking since it hides your IP address.

Opera is my main browser, and it includes a free built-in vpn. When I have it turned on, some websites refuse to load, claiming they are not allowed in "my country" so I assume it's working. My bank also makes me go through security questions, since it doesn't recognize me if it's on.

If you use free internet around town, or want to troll discussion sites, a vpn can be handy, but otherwise really isn't necessary if you've got your own secure router. And there's usually no reason to pay for one for personal use.

Others may have different views.

Hotspot Shield is another free one I've used, and it works on the whole computer, not just one browser.

Pros:

You can appear to most sites like you are coming from the location of the VPN server
(e.g. might be able to watch BBC because the VPN server is in the UK, though more and
more sites are keeping track of VPN servers and still block them).

Your real IP address is hidden except for the encrypted traffic to/from the VPN server.

Your ISP can't tell what sites you're using (other than traffic to/from the VPN server).

Cons:

All your traffic goes through the VPN server -- which can slow things down a lot.

All your traffic goes through the VPN server -- so *they* will know a lot about you.

The logs of the VPN server might be shared with someone/some govt you don't like
(e.g. I was researching one VPN service only to find it was hosted in Hong Kong).

Basically if you're mostly using web browsers, then your ISP can tell what sites you're visiting, but as long as the traffic is encrypted, they won't be able to tell much more than that (think addresses on envelopes vs. reading the contents of a letter).

It involves whether you value your privacy, or not. Modern computer tech offers companies, businesses, nefarious individuals with computer programming skills (aka 'hackers'), national security agency types, even just plain criminals the ability to track your activities on the Internet, usually with the aim of obtaining personal information at a minimum, what websites you visit, online banking, etc, and in the case of overseas criminals usually the goal is to just get your $$ from you. I did a search just now using a privacy minded search engine called 'ixquick' or Startpage (since even Google is a notorious privacy abuser online, tracking you just about everywhere you go online once you make the mistake of logging into a computer with a Google Gmail account): https://www.startpage.com/do/search?q=marketing+tracking+national+security+vpns&lui=english Those search results give a lot of websites talking about the issues of tracking, privacy, anonymity, security, etc, and how VPNs go about giving you an excellent degree of invisibility in terms of personal information you leak while web browsing, what IP address your online presence originates from, etc.

If you have a smart-phone, Android or iPhone, there are a lot of online VPN services that offer free trial or test client apps you can download to try out their VPN services. I personally use them, I've seen how they work, how once I am connected into a VPN service where my IP address comes out of an IP address on the other side of the country the ability of trackers to determine my identity in an effort to either collect data on my web browsing, banking, etc with a goal toward eventually stealing my identity, bank account information, etc basically disintegrates on them as I vanish into inscrutability on them.

I would recommend a few test sites to check your online presence right now. Try these out just connected to your regular ISP and see what they say about how easy it is for you to be able to be identified/tracked online:

https://ipleak.net/
https://browserleaks.com/webrtc
https://panopticlick.eff.org/

The best way to test your vulnerability to online tracking/stalking/data collection is with & without a VPN service connected. Web browsers are not all created equal, as are a lot of apps available for Androids & iPhones. The Google Chrome web browser is one of the 'leakiest' at dripping IP addresses, browser ID information that makes it easy for marketers to track your browsing habits, etc. I avoid it like the plague. The Firefox browser is a *little* better, but not by much. For desktop users there are 'extensions' or 'plug-ins' available for both Chrome & FF to help secure them a lot by closing up a lot of their leaky flaws/holes. Unfortunately those plug-ins/extensions a lot of times aren't available for smart-phone browsers. One of the best browsers imo is the Opera browser. It has a lot of security built into it, the smart-phone version is decent, the desktop version even has a built-in VPN function built into it. You could just download the Opera version for a desktop system, try one of those leak/tracking testing sites with the Opera VPN disabled, run the tests, then enable the built-in VPN, run the tests again and see for yourself quickly the effects of a VPN.

For smart-phones I consider VPNs a must. There are decent VPN services that give long deals where the service costs about $5/mo for over 1 year of service https://www.startpage.com/do/search?q=best+vpn+services+2018&lui=english There are also wireless router companies now building in the ability to run VPN services from the routers. I've used these kinds of services on my Linux router I built before. The effect is any machine connected to my Gigabit LAN behind the VPN in my Linux router would connect to the Internet and as long as I did not log into Google or any online services when I browsed the Internet or watched videos on YouTube Google had no clue who I was, or even what IP address I was coming from out of my ISP. That's kind of neat. I have a BluRay player which has online streaming service apps in it. A lot of times I would watch a video on Crackle and get commercials aimed at me coming from Texas or Santa Rosa, California, all over the place it seemed. So the shotgun nature of the ads being targeted at me via my Blu-Ray player behind the VPN while I was not logged into it let me know I was anonymous to those tracking my viewing habits. That's fine by me. Also when I logged onto Netflix and was tracked coming out of a VPN service I was still able to watch videos as my VPN exited in the U.S. So it's a personal choice, whether to use the VPN or not. In cases of smart-phones on the road, VPNs are a must imo. At home for viewing Netflix, not so much. If you're trying to avoid being tracked by Google/Amazon/etc online for desktop browsing, they're nice to have sometimes. If you're logged into Google and don't care how you're being tracked by them they're a waste of $. Also in order to get any decent privacy from Google after you've been logged in online in a browser for awhile it is necessary to completely clear your browser's search history, enable the VPN service, then restart the browser. At that point the cookie trackers are gone, your browser history starts fresh, any logins to Google you did before are gone, and you 'come out' into the Internet from the VPN's IP address, which makes you practically invisible to Google & the trackers/marketers/bad-guys, etc who were stalking you before, as they nearly always do, but that most people have no clue about.

Anyway, it's a personal decision for you, as I said to begin with it depends on whether you value your privacy or not.

Even better, I was cruising YouTube just now & found a pretty good video that explains about VPNs better than I can in a forum, + the guy brings up a lot of issues I didn't even consider in his explanation. This should help a bunch:

Look for VPN services that are overseas in countries that respect/value/codify-into-law-(or human rights) user privacy (primarily E.U. nations these days)

Look for VPN service providers with a large number of servers in as many nations around the world as possible

Look for VPN services that advertise ability to handle a large amount of data traffic on their networks at peak traffic times

Look for VPN services that don't keep user traffic logs (or at worst, recycle those logs every 24 hours)

The least important criteria to shop for VPN service providers by is price. Keep that at the bottom of your list when evaluating VPN services. What's most important is uptime, service availability/quality under heavy traffic times, and user log personal privacy policies.

There are other more technical issues to consider shopping VPN service providers. This site explains more about the various pros/cons in the different VPN apps & protocols: https://thebestvpn.com/pptp-l2tp-openvpn-sstp-ikev2-protocols/

I prefer OpenVPN myself, as I've used it and it is extremely secure/robust/fast. And so I tend to shop for VPN service providers best fitting my rules of thumb criteria that support OpenVPN clients.

Hint hint https://airvpn.org/