Millions of people are unaware of and uninformed about how their personal information is being used, collected or shared in our digital society.

A new investigation reveals today how cybercriminals are advertising valuable personal data about consumers involving some of the biggest shopping names.

Stolen accounts and data are being advertised for sale cheaply, with customers of Tesco, Deliveroo and McDonald’s among those having their personal information marketed by fraudsters.

January 28 has been earmarked Data Privacy Day and the aim is to inspire dialogue and empower individuals and companies to take action.

The consumer organisation Which? has offered advice to consumers on protecting their data.

READ MORE: Tesco, McDonald's and Deliveroo customers hit as fraudsters 'sell' stolen data on the dark web

Passwords – Always set strong passwords for your accounts and don’t use the same ones across different accounts.

The National Cyber Security Centre says that if hacker gets into your email, they could:reset your other account passwords and access information you have saved about yourself or your business.

An email password should be strong and different to all other passwords. This will make it harder to crack or guess.

Using three random words is a good way to create a strong, unique password that you will remember, the NCSC says.

You should also protect your other important accounts, such as banking or social media, they say.

The NCSC says: "When you use different passwords for your important accounts, it can be hard to remember them all.

"A good way to create strong, memorable passwords is by using 3 random words.

"Do not use words that can be guessed (like your pet’s name). You can include numbers and symbols if you need to. For example, 'RedPantsTree4!' 

"Saving your passwords in your browser  means letting your web browser (such as Chrome, Safari or Edge) remember your password for you.

"This can help make sure you do not lose or forget your passwords and protect you against some cyber crime, such as fake websites

"It is safer than using weak passwords, or using the same password in more than one place.

"Make sure you protect your saved passwords in case your device is lost or stolen."

Password manager – Many services now alert you if your passwords have been compromised. As services such as Lastpass and Dashlane can be used for free, there’s no reason not to use a password manager. Additionally, consumers can check if their email has been included in a data breach using https://haveibeenpwned.com/.

Two-factor authentication (2FA) – Wherever possible turn on 2FA to increase security, particularly if your account holds your financial information. Which says not to use SMS but use an authenticator app or even a hardware token if possible.

Some online banking uses 2FA automatically. It does this by asking for more information to prove your identity, such as a PIN, password or code  and or biometrics - a fingerprint or face ID

The NCSC says:  "Two-factor authentication (2FA) helps to stop hackers from getting into your accounts, even if they have your password.

Credit card details – Don’t save your credit card details if you aren’t going to use the service regularly. Although it’s a faff to resubmit them, that’s better than having your financial information unnecessarily stored in a database that could be compromised.

Guest checkout – Similarly to the above, just check out as a guest if you aren’t going to use the service regularly. Only create an account if you really need to.