WEB DESK: One of mankind's most generous gift is free wi-fi. But it is only a gift unless it is someone else's. It may be possible that someone you did not give permission to is using your wi-fi.

So how do you find out whether your network feels sluggish thanks to your household’s Netflix habit or thanks to an unauthorized user stealing your bandwidth?

Check your router’s administrative page

One way to see what devices are connected to your Wi-Fi network (and to check whether you recognize all of them) is to log on to your router’s administrative page and check its DHCP Client Table, DHCP Client List, or the list of Attached Devices. From there, you’ll be able to see all of the computers, smartphones, tablets, and any other devices connected to your wireless router.

Use an app to scan the network

If you don’t want to bother with logging in to your router’s administrative page, you can download an app that will do the dirty work for you. There are a number of apps that will scan your network for connected devices. In fact, your router’s manufacturer may have its own app, like Netgear’s Genie, Linkys Connect, or Apple’s AirPort Utility for iOS.

How to use the list to determine who’s using your Wi-Fi

Once you’ve gotten the app of your choice to show you a list of the gadgets that are connected to your network, you can determine which ones are yours, and see if there’s anything suspicious going on with your network. Your computer should show up, as well as your smartphone and your tablet (which you’ll probably be able to identify in the list by the manufacturer’s name).