Six technologies, and the problem each one solves
This chapter is easy to answer badly, because it is tempting to write enthusiasm instead of explanation. The marks go to students who can say what a technology does, why it is better than what came before, and what it is genuinely poor at.
Every one of these has a real limitation. Naming it is usually worth as much as describing the benefit.
| Technology | What it does | Its real limitation |
|---|---|---|
| Artificial intelligence | systems that perform tasks needing human-like judgement | reflects the bias in its training data; cannot explain itself |
| Cloud computing | computing power and storage rented over the internet | useless without a connection; data is on someone else's servers |
| Internet of Things | everyday objects with sensors, reporting over a network | cheap devices are rarely updated, so they are a security weak point |
| Blockchain | a shared ledger no single party can alter | slow and energy-hungry compared with an ordinary database |
| Augmented / virtual reality | overlays on the real world, or a simulated one | expensive hardware; discomfort over long sessions |
| Big data | analysing datasets too large for ordinary tools | correlations found by chance in huge datasets look convincing |
Cloud computing
Instead of buying a server, you rent one by the hour from a provider and reach it over the internet. That single change removes the largest barrier to starting a technology business: you no longer need capital to buy hardware before you have customers.
The advantages are scalability — take more capacity on a busy day and give it back afterwards — access from anywhere, automatic backup, and no maintenance staff. The disadvantages are equally concrete: nothing works without a reliable connection, ongoing rental can exceed the cost of buying, and your data physically sits on hardware you do not control, which raises legal questions about where it is stored.
- SaaS — software as a service. You use the finished application: Gmail, Google Docs.
- PaaS — platform as a service. You deploy your own code onto someone else's managed platform.
- IaaS — infrastructure as a service. You rent bare virtual machines and manage everything above them.
Why scalability is the point
A shop's website might need one server all year and forty for three days of a sale. Buying forty servers means thirty-nine idle for 362 days. Renting them for three days costs a fraction of that. Being able to grow and shrink on demand is the argument that wins in exam answers, more than "access from anywhere".
The Internet of Things
An IoT device is an ordinary object with a sensor, a small processor and a network connection — a thermostat, a water meter, a fitness band, a delivery tracker. Individually each is trivial; collectively they produce continuous data about the physical world that simply did not exist before.
The benefits are automation and monitoring: a farm can irrigate by soil moisture rather than by schedule, a city can time traffic lights by actual congestion. The problem is security. These devices are cheap, are shipped with default passwords, and are rarely updated — so they are the easiest way into a network, and compromised IoT devices have been assembled into some of the largest attacks ever recorded.
Why IoT security is genuinely hard
A laptop gets security updates for years. A cheap sensor may never receive one — the manufacturer has moved on, and the device has no interface to update it through. It then sits on the network for a decade with a known vulnerability. The fix is not clever software but buying devices from suppliers who commit to updates, changing default passwords, and putting IoT devices on a separate network from anything important.
Blockchain, and when not to use it
A blockchain is a ledger copied across many computers, in which records are grouped into blocks and each block carries a cryptographic hash of the one before it. Altering an old record changes its hash, which breaks every block after it, and the other copies disagree — so tampering is detectable rather than merely discouraged.
That property is valuable when no single party can be trusted to hold the record: cryptocurrency, supply-chain provenance, land registries in places where records have been altered. It is a poor choice when one organisation already owns the data and is trusted with it, because an ordinary database is faster, cheaper and uses a tiny fraction of the energy.
Before you leave this chapter
- For every technology, know what it does, one advantage and one real limitation.
- Cloud: scalable and maintenance-free, but useless offline and hosted on hardware you do not control.
- IoT: continuous data from the physical world, but a serious security weak point.
- Blockchain: tamper-evident and needs no trusted party, but slow and energy-hungry.
- AI: fast pattern recognition at scale, but inherits the bias in its training data.
Who manages what: the three cloud models
Exam questions about cloud computing very often come down to one diagram: how much of the stack the provider looks after, and how much is left to you. The trade-off is always the same — the more the provider manages, the less control you have and the less work you do.
Move from On-premises through to SaaS and watch the boundary rise. Every layer handed over is one less thing to maintain and one less thing you control — that is the whole decision, in one picture.
A way to remember the three
Think of transport. IaaS is renting a car — you drive, fuel and park it. PaaS is a taxi — you say where to go and someone else handles the vehicle. SaaS is a bus — the route, the vehicle and the schedule are all decided for you, and you simply get on.
Digital currency
A digital currency exists only in electronic form — no notes, no coins. Bank balances are already digital in that sense, but the term usually means a currency with no central bank behind it, of which cryptocurrency is the main example.
The problem any digital currency must solve is that data can be copied. If money is just a number in a file, what stops it being spent twice? Traditional systems solve it with a central authority — the bank keeps the definitive record. Cryptocurrency solves it with blockchain instead: every transaction is recorded in a ledger copied across many computers, each block carrying a hash of the one before, so an altered record breaks the chain and is rejected by the other copies.
- Advantages: transfers work across borders without a bank; transaction records are transparent and tamper-evident; no single organisation controls it.
- Disadvantages: the value can swing violently; the anonymity attracts criminal use; the computation involved consumes enormous amounts of electricity; and a lost key means the money is gone permanently, with nobody to appeal to.
The trade-off is the whole point
Removing the central authority is what gives cryptocurrency its independence and what removes every protection that authority provided. A mistaken bank transfer can sometimes be reversed; a mistaken cryptocurrency transfer cannot. A forgotten bank password can be reset; a lost private key cannot. Exam questions asking you to evaluate digital currency are asking you to weigh exactly that exchange.