Wi-Fi has been prevalent for quite some time. 
Short For Wireless Fidelity, Wi-Fi allows users to wirelessly connect to the internet with a much better speed as compared to say Bluetooth, 2G etc.
There are TWO Basic requirements for Accessing Internet over Wi-Fi: (A) Transmitter i.e a Wi-Fi Hotspot, & (B) Wi-Fi Enabled Equipment/Receiver.
However, ALL is not Dandy & Free in the Wi-Fi World. There are TWO TYPES of Wi-Fi Secured & Non-Secured.
A Non-Secured Wi-Fi is FREE!!. These are also called as FREE Wi-Fi HOT-SPOTS. They are hard to find. Try Places Like: Cafe Coffee Day, Barista etc…
However, MOST Wi-Fi Hotspots are PAID to USE. Whenever one attempts to get in through the Wi-Fi a Login page appears wherein we are supposed to provide our Credit Card Number (BAD!!). The moment you spot this, you should understand that this is a PAID Wi-Fi.
However, please note, Even with a Log-in Screen, it may be a FREE option! It might simply be a means to get a Registered User. Please check with the Service provider (i.e Ask the manager of the Bistro!).
Example: Pune-University’s Campus is Free Wi-Fi Enabled. However, you need a Student’s or a Professor’s Log-in details to use it!
There have been Three iterations / revisions to the Wi-Fi Standard. Namely IEEE 802.11b…802.11g… & Latest 802.11n.
I am not going into a history lesson about the Wi-Fi, Nor a jargon filled lesson between Difference between b, g & n Standards. However, I will illustrate the primary difference between the Three Standards & dispel the common misconception that Latest is Always the Greatest.:
We always demand the latest… Hence when the Draft “n” specification came out, people rushed to buy… NOT a safe option. the “n” Standard has a much higher range than previous “b”/”g”:
AND since very few people were security conscious they did not use the WPA/WEP (Basically a Password) accesses control. Hence, MANY snoopers (People who randomly try their luck to get free access to unsecured Wi-Fi. There are even Softwares that automate this process.. SCARY!) could easily gain access to Un-Secured Wi-Fi “Hotspots”:
I will mention some steps to SECURE YOUR Wi-Fi:
Here are 3 basic ways to keep your WiFi router or connection secure:
1. Change the router’s Default Username and Password.
Choose an uncommon username, something only you can know. Then choose a strong password – keep it at least 8 characters long, using a combination of letters, numbersand characters. Keep it secure and don’t share it with others. Basically…. Longer & weirder is Better 
2. Turn on Encryption.
Right now, the best encryption technology is WPA2. Select that one if your router supports it. If you’re still in the process of purchasing one, avoid routers that only support WPA (Wi-Fi Protected Access) and WEP (Wired Equivalency Privacy) and purchase one that supports WPA2. There are available tools on the Internet that can easily crack WPA and WEP encryption.
3. Change the Default SSID and Disable Broadcasting.
The SSID is your network name. By default, routers use a generic manufacturer SSID like “netgear”, “linksys” or “default”. Change it to something else, something uncommon. You can use the same principle as choosing/creating a strong password. A network using a default SSID can be perceived by the attacker as a weak and poorly configured network and will most likely attack it first. Another thing you can do with your SSID is to shut off or disable broadcasting. Keeping it “out of sight” will lessen the chances of it being attacked. Don’t worry about shutting this feature off because you can still connect to it manually.
I hope that this short tutorial on 3 ways to secure your WiFi router will help you keep your wireless router/connection safe. This is just a basic tutorial and I plan of coming up with a more detailed tutorial that includes more ways (some advanced ways) to keep your wireless connection/router secure so stay tuned for that. You can subscribe to receive FREE updates via email so you’ll be sure you won’t miss it.
Have you or someone you know had issues with online fraud, identity theft and other problems because of an open or unsecured wireless Internet connection? What measures are you taking to keep your WiFi connection safe and secure? Remember, its better to be safe than sorry.
Source: [JaypeeOnline]
Conclusion:
Wi-Fi can be Both, Free OR Paid.. Hence if you are “Consumer”, then check with the Service Provider… IF your are the OWNER of a Wi-Fi Transmitting Device (Wi-Fi ADSL Modem, Router), then Change settings to restrict access as mentioned above..
