s1) how do the brain function

Your brain is running right now, and it never stops, not even while you sleep. Three pounds of tissue inside your skull is doing more calculations per second than any computer on Earth. So how does it actually work? Let's break it down.

 The Neurons.

Everything your brain does starts with neurons, tiny cells that talk to each other using electricity and chemicals. You have around eighty six billion of them, and each one can connect to thousands of others, forming a network so complex that scientists still can't fully map it. When a neuron gets excited, it fires an electrical signal down its length, then releases chemicals called neurotransmitters to pass the message to the next neuron. This happens in milliseconds, thousands of times a second, all over your brain. Every thought, every memory, every movement you make is just neurons passing signals in patterns. The more two neurons fire together, the stronger their connection becomes, which is the basic rule behind learning and habit formation. Around these neurons sit support cells called glial cells, and for a long time scientists thought they just held everything in place. Now we know they clean up waste, feed neurons nutrients, and even help speed up signals by wrapping neuron fibers in a fatty coating called myelin. Without that coating, your reflexes would be noticeably slower, which is why damage to it, like in multiple sclerosis, causes such serious problems with movement and coordination. Your brain also runs on a surprising amount of energy for its size. Even though it's only about two percent of your total body weight, it uses roughly twenty percent of the energy you burn every single day, mostly just keeping all those neurons ready to fire at a moment's notice.

 The Brain Regions.

Your brain isn't one single unit. It's more like a team of highly specialized departments, each responsible for different tasks but constantly working together. At the base is the brainstem, which controls the essential functions you never have to think about, such as breathing, heartbeat, blood pressure, and keeping you alive every second of the day. Sitting just above it is the cerebellum, which fine-tunes your movements, balance, posture, and coordination, allowing you to walk, run, write, or even catch a ball without constantly losing your balance.

Buried deeper inside the brain is the limbic system, often called the emotional center. It helps create emotions, stores memories, and influences motivation and behavior, playing a major role in how you react to experiences. Covering everything is the cerebral cortex, the folded outer layer responsible for higher thinking, reasoning, language, creativity, problem-solving, and decision-making. Although each region has its own specialized role, they constantly exchange millions of electrical signals every second, allowing the brain to function as one seamless, connected system rather than a collection of separate parts.

The cerebral cortex itself is divided into four major lobes, each with its own responsibilities. The frontal lobe controls planning, decision-making, self-control, personality, and voluntary movement. The parietal lobe processes touch, temperature, pain, and helps you understand where your body is in space. The temporal lobe is responsible for hearing, language comprehension, memory, and recognizing faces and objects. Finally, the occipital lobe, located at the back of the brain, processes everything you see, turning light entering your eyes into meaningful images.

Damage to any of these areas can produce surprisingly specific changes in behavior or abilities. A person may lose the ability to speak clearly, recognize familiar faces, or control their emotions while leaving other skills completely intact. 

  The Two Hemispheres.

Your brain is split into two halves, left and right, connected by a thick bundle of fibers called the corpus callosum. The old idea that one side is creative and the other is logical is mostly a myth, both sides work together on almost everything you do. What is true is that each hemisphere controls the opposite side of your body, so your left brain moves your right hand, and your right brain moves your left. Certain functions do lean more to one side, language processing usually leans left, while spatial awareness often leans right. But real life thinking, like solving a problem or having a conversation, uses both hemispheres firing together, not one switched off while the other works alone. Scientists discovered a lot of this through patients who had their corpus callosum severed to treat severe epilepsy. Studying how their two hemispheres stopped communicating gave researchers a rare window into what each side handles on its own, and it confirmed that cooperation, not division, is how a healthy brain actually operates day to day. So the next time you hear someone describe themselves as purely a left brain or right brain person, you'll know the real science tells a much more connected story than that popular myth suggests.

  Memory Formation.

Memory isn't stored in one single spot, it's spread across your brain like pieces of a puzzle. When something happens to you, different parts of your brain record different details, the sounds, the emotions, the visuals, and a small structure called the hippocampus stitches them together into one memory. At first this memory is fragile and easily forgotten, but every time you recall it or sleep on it, your brain strengthens the connections involved, a process called consolidation. This is why sleep is so important for learning, your brain replays the day's events at night, deciding what to keep and what to let fade. Over time, frequently used memories move from the hippocampus into long term storage across the cortex, which is why old memories can survive even after certain injuries. There are also different types of memory working at once. Short term memory holds a handful of items for a few seconds, like remembering a phone number just long enough to dial it. Working memory lets you hold and manipulate information, like doing math in your head. And long term memory, once consolidated, can last a lifetime, though it's constantly being reshaped a little every time you recall it. That reshaping is also why eyewitness memories can be surprisingly unreliable, every time you retell a story, your brain reconstructs it rather than replaying an exact recording, and small details can shift without you ever noticing.

 Brain Plasticity.

Here's the most important part, your brain is not fixed, it's constantly rewiring itself based on what you do. This is called neuroplasticity, and it means every skill you practice, every habit you build, physically changes the structure of your brain. Neurons that fire together wire together, so repeated actions create stronger, faster pathways, which is why practice makes things feel easier over time. This also works in reverse, connections you don't use get weaker and eventually fade away. Even adult brains keep this ability, learning a new language, picking up an instrument, or simply changing a bad habit all leave a physical mark on your neural network. Your brain today is literally shaped by everything you've done up to this point, and it will keep changing based on what you do next. This is also the science behind recovery after brain injury, patients who lose function in one area can sometimes regain it because nearby regions rewire themselves to take over the lost job. It's slow, and it takes real effort, but it proves that the brain you have isn't permanent, it's a work in progress for your entire life. Studies on London taxi drivers even showed their hippocampus physically grew larger the longer they spent memorizing the city's complicated streets, solid proof that the demands you place on your brain literally reshape its structure over time.

So that's the basic story of how your brain works, billions of neurons, specialized regions, two connected hemispheres, a memory system built for learning, and a brain that keeps rewiring itself for life. It's the most complex object we know of in the universe, and it's sitting right behind your eyes doing all of this without you ever having to think about it. If you found this interesting, hit subscribe for more videos that break down how your body and mind actually work.