Understand anything, visually

Photosynthesis is the process plants, algae, and some bacteria use to turn sunlight, water, and carbon dioxide into glucose (food) and oxygen. It is the chemical reaction that powers almost all life on Earth and produces the oxygen we breathe.

A black hole is a region of space where gravity is so strong that nothing — not even light — can escape once it crosses the boundary called the event horizon. They form when massive stars collapse at the end of their lives.

Gravity is the force by which every object with mass attracts every other object. It's what gives things weight, keeps planets orbiting the Sun, and pulls a dropped apple back to the ground.

DNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for building and running every living thing. It's a long, twisted ladder — a double helix — whose rungs spell out a code in four chemical letters.

The water cycle is the continuous journey water takes through the environment — evaporating from oceans and land, condensing into clouds, falling as rain or snow, and flowing back to the sea. The same water has been recycled for billions of years.

Cellular respiration is how cells release energy from food by breaking down glucose using oxygen, producing carbon dioxide, water, and usable energy (ATP). It's essentially the reverse of photosynthesis and runs in nearly all living cells.

Climate change is a long-term shift in global temperatures and weather patterns. Today's warming is driven mainly by humans burning fossil fuels, which release greenhouse gases that trap heat in the atmosphere.

Newton's three laws of motion describe how objects move and respond to forces. Together they explain everything from a rolling ball to a launching rocket, and form the foundation of classical mechanics.

Plate tectonics is the theory that Earth's rigid outer shell is broken into large plates that slowly move on the hotter, softer mantle beneath. Their motion builds mountains, opens oceans, and causes most earthquakes and volcanoes.

Evolution is the process by which living things change across generations as heritable traits become more or less common. Driven mainly by natural selection, it explains the diversity of life and how species adapt to their environments.

Osmosis is the movement of water across a semipermeable membrane from a region of lower solute concentration to higher concentration, balancing the two sides. It's how cells take in and lose water.

The solar system is the Sun and everything bound to it by gravity — eight planets, their moons, dwarf planets, asteroids, and comets. It formed about 4.6 billion years ago from a collapsing cloud of gas and dust.

The greenhouse effect is the process by which gases in Earth's atmosphere trap heat, keeping the planet warm enough for life. Burning fossil fuels adds more of these gases, intensifying the effect and warming the climate.

Artificial intelligence (AI) is the field of building computer systems that can perform tasks normally requiring human intelligence — like understanding language, recognizing images, making decisions, and learning from data. Modern AI is driven mostly by machine learning.

Machine learning is a branch of AI where computers learn to make predictions or decisions by finding patterns in data, instead of being explicitly programmed with rules. The more relevant data it sees, the better it gets.

A large language model is an AI system trained on vast amounts of text to predict the next word in a sequence. That simple objective lets it write, summarize, translate, answer questions, and hold conversations.

A neural network is a computing system loosely inspired by the brain, built from layers of simple connected units ('neurons') that learn patterns from data. They power most modern AI, from image recognition to language models.

A blockchain is a shared digital ledger that records transactions across many computers so the record can't be changed retroactively. Each 'block' of data is cryptographically linked to the one before it, forming a tamper-evident chain.

The internet is a global network of computers that communicate using shared rules (protocols), letting any connected device exchange data with any other. The web, email, and apps all run on top of it.

Cloud computing is using computing resources — servers, storage, software — over the internet instead of on your own machine. You rent capacity on demand from providers and access it anywhere, paying for what you use.

Compound interest is interest earned not only on your original money but also on the interest it has already earned. Over time this snowball effect makes savings and investments grow faster and faster.

Inflation is the rate at which the general level of prices rises over time, which means each unit of money buys a little less than before. Moderate inflation is normal in a growing economy; very high inflation erodes savings quickly.

The stock market is where shares of public companies are bought and sold. A share is a tiny piece of ownership in a company, and its price moves with supply, demand, and expectations about the company's future.

An interest rate is the cost of borrowing money, or the reward for saving it, expressed as a percentage. It sets how much extra a borrower repays and how much a saver earns over time.

Opportunity cost is the value of the best alternative you give up when you make a choice. Every decision has one — the time, money, or option you didn't pick.

Marketing is everything a business does to understand its customers and connect the right product with the right people — from research and messaging to pricing, distribution, and advertising. Its goal is to create and communicate value so customers choose you.

Supply and demand is the core model of how prices form in a market. Demand is how much buyers want at each price; supply is how much sellers will provide. The price settles where the two balance.

Globalization is the growing interconnection of the world's economies, cultures, and populations through cross-border trade, investment, technology, and the movement of people and ideas — making distant markets and supply chains deeply interdependent.

The Pythagorean theorem states that in a right-angled triangle, the square of the longest side (the hypotenuse) equals the sum of the squares of the other two sides: a² + b² = c². It lets you find an unknown side when you know the other two.

A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself. 2, 3, 5, 7, and 11 are primes — they're the building blocks of all other numbers.

Recursion is when a function solves a problem by calling itself on a smaller piece of the same problem, until it reaches a simple case it can answer directly. It's a powerful way to express problems that contain smaller copies of themselves.

An algorithm is a precise, step-by-step set of instructions for solving a problem or completing a task. Recipes, search engines, and GPS routes all run on algorithms.

Binary is a number system that uses only two digits, 0 and 1. Computers use it because their circuits have two states — on and off — so every piece of data is ultimately stored as binary.

A cognitive bias is a systematic error in thinking that affects the decisions and judgments people make. Our brains use mental shortcuts to act quickly, and those shortcuts sometimes lead us reliably astray.

Classical conditioning is a type of learning where a neutral cue becomes linked to an automatic response after being paired with a stimulus that naturally triggers it. Pavlov's dogs salivating at a bell are the classic example.

The French Revolution (1789–1799) was a period of upheaval in France that overthrew the monarchy, ended feudal privileges, and reshaped Europe around ideas of liberty, equality, and citizenship. It began amid financial crisis and deep inequality.

The Industrial Revolution (roughly 1760–1840) was the shift from hand production to machines, factories, and steam power that began in Britain and transformed economies and daily life — moving people from farms to cities and launching the modern industrial world.

The immune system is the body's defense network — a coordinated set of cells, tissues, and organs that detects and destroys harmful invaders like bacteria and viruses, and learns to recognize threats it has met before.

The nervous system is the body's communication network — the brain, spinal cord, and nerves — that senses the world, processes information, and controls everything you think, feel, and do, using fast electrical and chemical signals.

Democracy is a system of government in which power comes from the people, usually through free and fair elections. Citizens choose their leaders and hold them accountable, with rights and the rule of law protecting everyone.

A metaphor is a figure of speech that describes one thing as if it were another to highlight a likeness — not literally, but to create meaning or vividness. 'Time is money' is a metaphor.

Color theory is the set of guidelines for how colors relate, mix, and combine to create harmony or contrast. It helps artists and designers choose palettes that look balanced and convey the right mood.

Fermentation is a process where microbes like yeast and bacteria break down sugars into simpler substances such as alcohol, acids, or gases. It's how we get bread, yogurt, cheese, beer, and many pickles.