Exercises: E-commerce

List three checks you should carry out on an online store before paying, and explain what risk each one prevents.

Explain the difference between paying by card, using a digital mobile wallet, and paying cash on delivery, and state one advantage of each payment method.

The figure shows the workflow of a secure online purchase.

Before the payment, a step marked with a question mark is missing. Describe what checks that step includes and explain why the final step—saving the confirmation and the invoice—is also part of purchasing securely.

Online stores detect when you leave an "abandoned cart" and follow up with reminders and coupons. Explain what tactic they use, how they know you were browsing, and how you can turn this tactic to your advantage.

When paying online, your bank sends a code to your cell phone to confirm the transaction (3-D Secure). Explain what additional security factor this step adds, and what happens if someone knows your card numbers but does not have your phone.

Explain the differences between buying from a professional seller and a private individual on a secondhand app: warranty, returns, liability if the product is counterfeit. What protections do you lose when buying from a private individual?

Before buying clothes online, it is a good idea to read the return policy. State four details you would check (time limit, who pays for return shipping, required product condition, return location) and explain what problem each one prevents.

Many games allow you to buy content (skins, coins, passes) with a single click. Explain how these in-game purchases differ from a standard purchase in a store, why it is advisable to ask for permission at home, and what you would check regarding saved payment methods.

A website offers sneakers worth $\$120$ for only $\$24$ "today only" and accepts a wire transfer in advance as the only payment method. Analyze the warning signs of fraud in this offer, explain why a wire transfer is the riskiest payment method in this case, and describe what you would do.

Explain what a digital invoice is, what minimum information it must contain, and what advantages keeping it offers over a paper receipt when you need to make a warranty claim.

An app offers a "seven-day free trial" and then charges $\$8.99$ per month with an almost invisible notice. Explain what design tactics it uses to make you forget to cancel (dark patterns), how to organize yourself to avoid overpaying (calendar reminder, checking bank statements), and what rights you have if you have already been charged.

An unfamiliar store has a 4.9-star rating with five hundred generic reviews ("Great!", "Perfect") almost all published in the same month. Explain how to detect paid-for reviews, what signs reveal they are fake, and how much weight you give to ratings when making a purchasing decision.

Compare a debit card linked to a family bank account and a reloadable prepaid card for supervised online purchases by a minor: what limitations each imposes, what happens if the card number is leaked, and which one you would choose to start with, justifying your answer.

For a gift worth $\$50$ you can buy at a local neighborhood shop or from an online retail giant. Compare price, speed, ease of returns, customer service, and local impact, and argue a reasoned decision for this specific case.

When checking out an order of 24.50 dollars on a web store, the system offers you three payment methods:\n- Option A: Save the card in the store and activate "1-click checkout".\n- Option B: Manually enter the card number, expiration date, and CVV on each purchase, without saving them.\n- Option C: Generate a single-use virtual card linked to a maximum balance of 25.00 dollars from your bank's app.\na) Analyze the technical difference between storing your banking details directly on the store's servers and using a gateway with "tokenization".\nb) If the store were to suffer a security breach and its database were leaked to the internet, predict the consequences for you in each of the three options.\nc) Justify which option you would choose to balance convenience and cybersecurity, and which two-factor authentication mechanism (SCA / 3D Secure) would come into play.

Your grandmother wants to shop online for the first time and has received this link via text message: "Professional blender for 14.99 dollars (previously 89.90 dollars), offer valid today only", which leads to the website www.chollos-hogar-express.top.\na) Carry out a security audit of the link: identify four technical and legal elements that you should check on that page before entering any data (certificate and protocol, legal notice and tax ID (EIN), contact channels, and available payment gateways).\nb) Predict the specific risks she faces if she enters her bank details on that page.\nc) Design a simple four-step protocol for an elderly member of your family to independently check whether an online store is legitimate before buying.

Three people search simultaneously for the same hotel room for the same dates and get these prices:\n- User A (desktop computer, 1st visit, accesses through a price comparison site): 78.00 dollars.\n- User B (high-end smartphone, 4th visit in 48 hours to the same hotel, official app): 98.50 dollars.\n- User C (mid-range smartphone, 1st visit, incognito tab on a 4G cellular network): 84.00 dollars.\na) Interpret which digital tracking mechanisms (cookies, device fingerprinting, demand history) explain the 20.50 dollars difference between User A and User B.\nb) Design a verification experiment with three technical steps to check whether an online store is applying dynamic price discrimination to you.\nc) Justify whether this practice complies with ethical principles and personal data protection legislation in e-commerce.