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Compiled languages translate source code into machine code before execution. Interpreted languages translate and execute it during execution. The distinction is genuinely blurrier than the textbook
Technical debt is the accumulated cost of choosing an expedient implementation over a better one. The metaphor, coined by Ward Cunningham, is precise and worth taking seriously: you borrow time now
Big O describes how an algorithm's cost grows as the input grows. It is a statement about the shape of the growth curve, not about speed in any absolute sense. What it deliberately ignores: Constant
A process is an independent running program with its own memory space. A thread is a unit of execution inside a process, sharing that process's memory with its sibling threads. What a process owns:
Entropy is a measure of how many different arrangements of a system's parts would look the same from the outside. High entropy means many arrangements produce that appearance; low entropy means very
Two reasons: heat left over from the planet's formation, and heat still being generated now by radioactive decay. Together they account for the roughly 5,000–6,000°C at the inner core — comparable to
Fission splits heavy atoms. Fusion joins light ones. Both release energy, and both do so for the same underlying reason. Why either releases energy. The binding energy per nucleon — how tightly
Absolute zero is 0 kelvin, equal to −273.15°C. It is the lowest possible temperature: the point at which a system has the minimum energy physically permitted. What temperature actually measures.
Blood types are determined by molecules on the surface of red blood cells — mostly sugars and proteins — that your immune system recognises as belonging to you. The ABO system. Red cells may carry
Fire is not a substance or an object. It is a process — a self-sustaining chemical reaction — and what you see is the visible byproduct of that reaction. The chemistry. Fire is rapid combustion: fuel
This turns out to be a genuinely subtle question, and the explanation most people were taught is largely wrong. The common answer — gyroscopic effect — holds that spinning wheels resist tipping.
Half-life is the time taken for half the atoms in a sample of a radioactive isotope to decay. It is a fixed property of each isotope, unaffected by temperature, pressure or chemical state. Why it is
Because rivers have been carrying dissolved minerals into the sea for billions of years, and the salt has nowhere to go. The main source is rock weathering. Rain is slightly acidic — atmospheric
Because the Moon is tidally locked to Earth: it rotates on its axis exactly once for every orbit it completes. The two periods are synchronised, so the same hemisphere always faces us. A common
A vehicle history check — HPI check, or equivalent from several providers — searches industry and government databases for facts about a specific vehicle that a seller may not disclose. It is one of
Because it is usually far larger than fuel, insurance, tax and servicing combined — and it is invisible, since you never write a cheque for it. What depreciation is. The fall in a vehicle's value
Both describe a car not turning as much as the steering input asks, but the end that loses grip differs — and so does what the car does next. Understeer is when the front tyres lose grip. You turn
Slipping — the period when the clutch plate and flywheel are rotating at different speeds while in contact. That is when friction material is being ground away, and every technique that extends it
They all match engine speed to road speed. The differences are in how they change ratio, and each has a distinct character. Manual. You select gears with a lever and disengage drive with a clutch
AdBlue is a solution of 32.5% urea in deionised water, used to reduce nitrogen oxide emissions from modern diesel engines. It is a consumable, not a fuel additive, and it goes in its own separate
Because they contain small quantities of extremely valuable precious metals, and they are unusually easy to remove. What is inside. A catalytic converter contains a ceramic honeycomb coated with
They are entirely different things, and treating one as covering the other is a common and expensive mistake. An MOT is a legal roadworthiness test, required annually in the UK for most vehicles over
It recovers kinetic energy that conventional braking would waste as heat, converting it back into electricity to recharge the battery. Conventional friction braking works by converting the vehicle's
A turbocharger forces more air into the engine than it could draw in by itself, allowing more fuel to be burned and more power produced from a given engine size. How it works. Exhaust gases leaving
Because metal expands when heated, and if one part of the pan expands faster than another, the resulting internal stress bends it. The technical term is thermal shock when it happens suddenly. The
Through a bimetallic strip and a small steam channel — an entirely mechanical arrangement with no electronics or temperature sensor involved. The bimetallic strip is the key component. It is two
Usually because it is recirculating rather than ducted, and most people do not know which theirs is. Ducted (extracted) hoods take air and expel it outside through ductwork. Steam, grease, smells and
All three remove moisture from clothes with warm air. They differ in what happens to the moist air afterwards, and that determines installation requirements and running cost. Vented. Heats air,
Because an induction hob does not produce heat at all — the pan is the heating element, and only certain metals can perform that role. How it works. Beneath the glass surface is a coil of wire
Fridge: 0–5°C, with 4°C or below recommended. Freezer: −18°C. These are the figures used by food safety authorities in the UK, EU and US, and there is solid reasoning behind each. Why 5°C for the
Because a fridge does not create cold — it moves heat out of the interior and dumps it into the room. That heat has to go somewhere, and if it cannot escape, the appliance cannot work properly. How
They indicate which heating elements and the fan are active, and choosing the right one matters more for results than the temperature does. The common symbols: A fan in a circle — fan oven
Dishwashers combine high temperature, prolonged wetting, and strongly alkaline detergent. Each damages particular materials, and the alkalinity is the part people underestimate. Cast iron and carbon
Wattage is the power output, and it determines how fast food heats. A 1,000W microwave heats roughly twice as fast as a 500W one. Two figures appear on microwaves and they are different. The output
Because the first portion of the transfer is being absorbed by a fast cache, and once that cache fills you see the device's real sustained speed. On SSDs: the SLC cache. Most consumer SSDs use TLC or
The monitor is reporting that it is powered and awake but receiving nothing on the selected input. That narrows the problem considerably — the monitor works, so the fault is upstream of it. Check in
A file is corrupted when its stored bytes no longer represent valid data for its format. The causes are varied, and most are about interrupted writes rather than data spontaneously degrading.
Echo happens when sound from your speakers is picked up by a microphone and sent back — creating a feedback loop where participants hear themselves delayed. The key diagnostic point: the person who
The causes split into surface, hardware, interference and software, and they are distinguishable with a few quick tests. Surface problems, which are the most common and most overlooked. Optical and
Because browsers are independent implementations of enormous standards, and the differences are usually in one of a handful of places. Extensions are the most common cause by far. Ad blockers,
Because safe mode starts the system with the minimum required to run — and if the problem disappears, the cause is something in what was excluded. What safe mode does not load: Third-party drivers.
Almost always congestion, and there are two separate kinds — one inside your home and one outside it. Outside your home: ISP contention. Broadband is sold on a shared basis. Many households share
Because the things occupying the space are usually not the things you were deleting, and much of it is invisible in the ordinary file view. The usual culprits, roughly in order: App caches. Apps
Because it discards accumulated state and returns the system to a configuration that was tested and known to work. What builds up while something runs: Memory problems. Memory leaks occur when a
A DDoS — distributed denial of service — attack overwhelms a service with traffic until it cannot serve legitimate users. The goal is not to steal data or break in; it is simply to make something
It refers to the width of the data a processor handles at once, and more importantly to how much memory it can address. The practical consequences are almost entirely about memory. The memory limit
They do it out of habit and outdated compliance requirements. Current expert guidance advises against it, and the reversal is now well established among standards bodies. The original reasoning. If a
Lossless compression can reconstruct the original data exactly. Lossy compression discards information permanently to achieve much smaller files. Lossless works by finding and encoding redundancy
A zero-day is a security flaw that the vendor does not yet know about, or has known about for zero days — so no patch exists and defenders have had no opportunity to prepare. The related terms are
In data centres — large buildings full of servers, owned by a handful of companies, in specific geographic locations. There is nothing ethereal about it. "The cloud" is a marketing term for someone