If you're using WPA2 encryption for your wifi and have set a reasonable password, you probably have nothing to worry about.

It's a best practice to shut down internet-accessing devices when not in use, like overnight, and you can be 100% certain that nothing is available on a device that's turned off. Besides, I thought Chromebooks used cloud storage rather than hard drives. If yes, that makes an outsiders's access to anything personal of yours from crawling up your internet access pipe much less likely because there's little or nothing there to find.

Thanks for this, Snidely (as I recall--hope right). I don't know what WPA2 encryption is.

I do shut off both desktop and the new Chromebook every night.

But can someone access my wifi when it is on?

Who set up your internet and wifi connection, someone you know or the company providing the service (like the phone or cable companies)? You should contact them and tell them you want to make sure your wifi signal is "encrypted with WPA2 and not open". There are different flavors of encryption (encoding) for wifi signals and WPA2 is the strongest/hardest to break into.

It's easiest if the person helping you is in your home to make the changes. If and when your wifi signal has strong encryption (WPA2) and a good password, then the potential for an outsider to connect to your wifi signal is very, very low. If your PC is off at the time, all they could do is use the connection and not access any personal information. Even if that's done when you're using it, it's not likely any personal information is at risk. After the person makes the router changes, they may need to change the settings on your Chromebook for you so that you can continue to use it.

I don't want to try to give you instructions on how to assess and change (if necessary) your router settings because from a distance I might make your situation
worse.

Good luck

What Elmer said: It's the wifi ROUTER that needs to be solidly protected.

Have a friend come over with something wireless. See if they can see your router (that's OK) and connect to it (not OK).

Thank you for these replies. I have done that and they need my password to connect via my wireless. But when the wireless is open and being used in my house, can anyone else nearby use my wireless? I guess that's what I'm trying to understand.

Can you be more specific - who is it that set it up? If "they" did so, why wouldn't "they" have your password?

If this is a system-supplied device - like from your cable or phone company - there should be a standard password. Or, sometimes they write the password on the bottom of the router. If this is a brand like Linksys or others, there is a standard default username and password that works for all of a product line - it's typically "admin" and "password".

Otherwise, devices can often be reset and they revert to the manufacturer's default settings.

If the wifi signal isn't encrypted, then yes, anyone can connect to it. Just like walking into a McDonalds or coffee store that has open wifi.

My desktop is via cable broadband--the company set it up. Have had it for many years and no problem. The wireless is thru a Netgear router that the tech person who helps me set up. I have my own password. I have had it for a couple of years but this is the first wireless device I have bought so am just now using wireless. But visiting family have used it tho they have needed my password to log in.

I'd like to leave it on all day so I can use the Chromebook. So is that secure--to leave it on?

Click around where your WiFi icon is on your Chromebook. You should be able to see a Properties or Info page which lists details about your WiFi connection. If you see 'WPA2' here, you are good to go.

If you want to be paranoid (and I do), the password you enter to connect to your WiFi network -- i.e., your WiFi password -- should be long and difficult.

Every device that connects to your WiFi network will need your WiFi password. So even if you are connected to your WiFi network from your Chromebook or phone, a random passerby can not "piggyback" that connection. They must enter your WiFi password on their device to connect.

You can safely save this WiFi password on your Chromebook so you don't have to enter it again and again. If someone breaks into your home and turns on your Chromebook, they will not be able to see your saved WiFi password. Furthermore, the intruder will need to guess your Google login/password to be able to log in and use your Chromebook.

Basically, if you see 'WPA2', you are good.

Thanks so much for this. Very helpful. I appreciate all the replies on this question.

WiFi routers typically have optional security protocols to either allow or block devices based on the MAC address. MAC does not mean Apple Macintosh. It's Media Access Control ... every network device has a MAC address hard-wired into it during manufacture (different than an IP address). Routers can be set to either block or allow a specific list of MACs. Set up the list for allow and then only that specific list of devices can connect to the WiFi (they must also have the correct WiFi password). Any device not on the MAC list is blocked, even if it has the correct password.

Forgot that Chromebooks allow anyone with a Google account to sign in. In the scenario above where an intruder can't use your Chromebook, you would have to lock it down first: https://support.google.com/chromebook/answer/1059252?hl=en