Steam Guard Mobile Authenticator - should I use it/how to use it

it adds protection and if someone wants to log in, they have to have your code from your phone, that's all I know

IF possible ALWAYS use 2FA (Two-Factor Authentication), everywhere possible. Add extra level of protection by using your personal device (smartphone) as confirm you are you (work like password that change every 30s)

You don't need a SIM card to use the app on a tablet or smartphone. But it's obviously a good idea to register a mobile phone number too, in your Steam settings.

how it works
https://i.imgur.com/LgIPcfT.jpeg

It's basically like email code confirmation but on your mobile phone(which is better as you need your phone to confirm it, meaning locally not online)
And it's called 2FA, as mentioned in above comments
For example, you login to your steam and it asks for you to confirm in your email (by pressing on link)... Instead you can confirm with your phone

Plus you can login by scanning QR code, no need to enter password

the three people who voted no don't own a mobile phone.

MFA or 2FA is the current security standard. It is not foolproof, because nothing ever is. But combined with using a different password (and ideally a different email) for each service, it allows for much stronger security than just a plain username / password authentication. You should definitely be using MFA/2FA for every service that offers it.

I've been using the mobile version of steam's 2FA for years without issue, knowing that in theory they can't hack my account without access to my phone gives me some peace of mind regardless of how true it might end up being in reality. Also the app allows you to have several steam accounts linked to the same phone so if you have more than one it makes managing them easier.

I don't think you actually need a smartphone. You can probably just Bluestacks on your PC and install the app, no?
Bluestacks or any other more recent android emulator.

You should use definitely use Steam Guard, it's an added lair of protection for your Steam account.

Here's the link about it all, you should take time to read it and understand how it works.
https://help.steampowered.com/en/faqs/view/7EFD-3CAE-64D3-1C31

Also upgrading away from Windows 7 will help you from not getting hacked :-)

I use it, quick login by scanning qr code, approving login through your phone, I think phone number is not needed, just install the app and add your account. Extra layer of protection, basically like an email confirmation that it's you trying to log in but through a phone app.

install on phone. Enter steam login password. It will give you a special R code for recovery a master number. Write it down somewhere. Then it should work. Eerytime you login soemwhere it wills end approval request and alternativel;y can generate steam guard code. Will need approve market sale items listed there.

Because the OP states that he is not very tech-savvy, maybe it is useful to explain in simple terms what 2-factor authentication is:

What is 2-Factor Authentication (2FA)?

2FA is an extra layer of security for your steam account (or for any other online account).

• Normally, you log in with just your username and password.
• With 2FA, you also need a second step to prove it’s really you.

Think of it like this:

Your password is the key to your front door.
2FA is like needing a second key or code sent to your phone to get in.

How is 2FA used on Steam?

Steam uses a system called Steam Guard for 2FA. You can enable it in two ways:

1. Email Code (less secure)

• If you don’t use the mobile app, Steam sends a verification code to your email.
• You must enter this code after your password.

Make sure your email account has a strong password that is not the same as your steam password!

2. Steam Guard Mobile Authenticator (most secure)

• You install the Steam app on your smartphone.
• When you log into Steam, the app shows a special code that changes every 30 seconds.
• You must enter this code after your password to log in.

Another method of using the Steam Guard mobile app is scanning a QR code.
It is the easiest and fastest option to use because it requires no typing at all.

• Instead of typing your username and password, you can choose “Scan a QR code with the Steam mobile app.”
• Steam shows you a QR code on the screen.
• You open the Steam app on your phone (with Steam Guard enabled).
• Tap the QR scanner icon in the app and scan the code on your computer screen.
• If it’s you, the app will show a message asking you to approve the login.
• Once you approve, you’re logged in — no password or code typing needed!

Why is 2FA useful?

Even if someone knows your password, they can’t log in unless they also have:

• Your phone (for the mobile code), or
• Access to your email (for the email code).

This helps to protect your steam account from hackers.

Yes it adds fool proof security, because u have to scan qr code and then verify login from your steam app(it also shows login location and ip). Which makes 99% impossible for hackers to hack your account.

it adds protection and if someone wants to log in, they have to have your code from your phone and it notife you as somebody try to log in your account on the steam app and show the place where somebody try to log in soo if it not you you can denied it treu the app