What is the immune system? A quick 101

A quick video on how your immune system works

Explore how your immune system’s vast network of cells, tissues, and organs coordinate your body’s defenses against bacteria, viruses and toxins with this 5-minute TED talk video.

An interactive dive into the immune system

Our bodies are equipped with an incredible system able to fight off invasive pathogens to protect us from illness. The complicated system includes lymph nodes, the spleen, bone marrow, and even the tonsils. But this same system can turn against itself, a condition known as autoimmune disorders. Follow along with this thorough, engaging explainer on the human body's defense system.

How do vaccines work? Watch this brief 101

Watch this under-3-minute video explaining how vaccines use the body's immune system to prepare our bodies against viral and bacterial threats to our health.

What are 'antibodies'? Read this quick overview

Antibodies are protective proteins produced by your immune system. They attach to antigens (foreign substances) and remove them from your body. Understand this important element of the immune system with this quick overview.

What is a cell? A great quick overview.

YourGenome.org furnishes a collection of information on cells and how they work. Every body has trillions of cells, each serving a specific function: making proteins, processing chemicals, and creating energy. Every cell contains a genome, a set of instructions for the cell's function. Brush up on your cells for a better grasp on genetics.

Human anatomy 101: the body's systems

Human life is made possible by the body's ten major systems, which maintain homeostasis by responding to incoming sensory and biochemical input. Each system must work independently and collaboratively for the body to maintain health and respond appropriately to its internal and external environments. The bones of the skeletal system, for example, give the body its shape and protect organs while also facilitating movement with the muscular system.

What is vaccination? The World Health Org explains

Read up on the basics of vaccinations with this 101 from the World Health Organization, the public health arm of the United Nations.

An interactive guide to the cardiovascular system

The cardiovascular or circulatory system moves blood throughout the body, ensuring cells have necessary nutrients and removing any waste. Click through this interactive 3D guide to explore the system as it crisscrosses the body via arteries, veins, and capillaries. This guide also includes similar breakdowns of the body and its other processes.

The immune system is in a constant fight against mutations

At the heart of cancerous cells is the development of mutations—an ongoing and continuous process that happens frequently. So why don’t we get cancer immediately? The body’s immune system has developed intricate methods to detect and destroy cancer cells, catching the vast majority before they get the chance to evolve into tumors.

What is immunotherapy and how does it work?

Immunotherapy is a type of treatment that harnesses the body's immune system to combat cancer. This video explainer from the American Cancer Society discusses various types of immunotherapies and their roles in targeting cancer cells. Still a new and quickly evoliving field, immunotherapy represents a significant advancement in cancer treatment and offers new options for patients.

Herd immunity works by slowing down viral transmission until it dies out

Herd immunity refers to a population whose vaccination rates against a given virus are high enough that transmission dies out before the bug can find the next unvaccinated person to infect. Rates needed to achieve this depend on how contagious a virus is. This video gives a quick visual explanation of how it works.

The science of food allergies

Why do certain substances trigger an immune response while others don't? Listen to researchers explain the science in this five-minute video. Food allergies affect around 8% of children and 2% of adults in the US, and—unlike sensitivity or intolerance—they involve the immune system mistaking certain harmless proteins in foods as dangerous invaders, triggering a rapid and sometimes severe defense response.

An overview on germ theory, the crucial framework developed by Louis Pasteur

Germ theory of disease is based on the concept that many diseases are caused by infections with microorganisms, typically only visualized under high magnification. Read this general overview to understand the basic framework which allowed for development of vaccines.

Fevers are an immune response to create hurdles for pathogens

Substances called pyrogens prompt the brain to raise the body temperature to levels where bacteria and viruses struggle to survive. The higher temps also support immune cells fighting off the invaders.

Tattoos, explained

Tattoos last because immune cells trap ink beneath the skin—but there's more to the story. This overview looks at how ancient cultures used tattoos for status, spirituality and punishment; how technology like the electric tattoo machine transformed the art form, and where innovations like smart tattoos could take it next.

Explore this deep dive into how SSRIs work

This 101-style explainer on selective serotonin reuptake inhibitors explains how they work in the brain—complete with classroom-style whiteboard drawings. It covers common SSRIs, why someone might try this medication, and a deeper discussion about potential side effects.

Dispose of invading viruses while learning about the CRISPR immune system

In this free, easy-to-play game, defend the city of Bacterium by playing the role of Cris Perotein. As you play, you'll learn microbiology and the workings of the mechanisms that CRISPR uses to protect bacteria. (desktop recommended)

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

How the body produces urine

Things seem so simple when nature calls. But, how does the body actually produce the urine we so regularly and thoughtlessly expel? This detailed, comprehensive animation walks viewers through every step with precise illustrations, from the kidney's filters (known as nephrons) to the direct nerve connecting the bladder to the brain. See how the body does it here.

Watch what the Ebola virus does inside the body in order to spread and survive

Once infected, the virus targets the body's immune cells, spreading the infection throughout the body. Patients exhibit severe flu-like symptoms. Ebola then targets the liver, which produces proteins that help blood clot, and the adrenal glands, which control blood pressure. The immune system may overreact to the viral invasion, releasing a cytokine storm that can result in shock, multiple organ failure, and death.

Tattoos remain visible on your skin thanks to immune cells called macrophages

What is a microbiome (and why are they important)?

Jump to: What is the microbiome? How microbiota benefit the body The role of probiotics Can diet affect one’s microbiota? Future areas of research What is the microbiome? Picture a bustling city on…

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

A gallery of medical illustrations from NIH

The National Institutes of Health provides educational materials for broad use. The institute hosts a Flickr account with many different image galleries, including this one (with over 70 images to date) that illustrate and annotate curious phenomena, from the life cycles of a malaria parasite to the comparison of male and female bladders. Explore the gallery here.

What is the blood brain barrier?

Every blood vessel is lined with endothelial cells that act as filters between blood and the rest of the body. In the brain, these cells are tightly packed together to keep a close watch on what substances can access the vital organ. This protective measure poses an obstacle to drugmakers looking to deliver drugs to the well-defended brain for conditions like Alzheimer's. Watch a quick overview here.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

An explanation of TCP/IP, which helps transmit data across the internet like a club sandwich

The system consists of several layers—application, transport, internet, and network—each responsible for specific tasks. These include interacting with a web browser, checking for errors, sending packets of data across various networks to avoid congestion on their way to a destination address, and managing the transmission of information across hardware, such as an Ethernet cable.

How to prepare for cyberattacks

An easy-to-digest checklist on the many ways you want protect yourself from a cyberattack before it happens, if it happens, and after it happens.

AI vs. machine learning vs. deep learning

Machine learning is best understood with visuals. A collection of the best 9 images, videos and flowcharts that explain what it is and how it works.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

This poison ivy knowledge quiz—accompanied by photos of the plant's varied forms—may help you identify this common rash-inducing growth.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Calculate how much of your tax dollars go to each federal program based on your income, filing status, and number of children

This site reaches millions of visitors who are tired of AI chatbots and seeking human connection. Pretend to be an AI chatbot and ask questions, provide answers, and draw for people in real time.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

See these 16 pieces of art evoking phobias of snakes, flying, spiders, and more. 

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

Learn how to read a prospectus, the juicy document that any company must file with the SEC before going public.

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

The name 'Silicon Valley' arose from the founding of Shockley Semiconductor Laboratory in Fairchild Semiconductor in 1956-57, founded near Stanford University in Palo Alto

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'