The physiology of a neuron

A neuron is simply an electrically excitable cell that receives, processes, and transmits information through electrical and chemical signals. Dendrites extend from the neuron cell body and receive messages from other neurons. When we say that neurons receive or send messages, what we actually mean is that they transmit electrical impulses along their axons. Lastly, neurons are excitable. In other words, the right impulse supplied to a neuron will produce electrical events, known as action potentials. When a neuron reaches its action potential (or spikes), it releases a neurotransmitter, which is a chemical that travels a tiny distance across a synapse before reaching other neurons. Any time a neuron spikes, neurotransmitters are released from hundreds of its synapses, reaching the dendrites of other neurons that themselves may or may not spike, depending on the nature of the impulse. This is the very mannerism that allows these vast networks of neurons to communicate, compute, and work together to solve complex tasks that we humans face daily:

So, all a neuron really does is take in some electric input, undergo some sort of processing, and then fire if the outcome is positive, or remain inactive if the outcome of that processing is negative. What do we mean here by whether an outcome is positive? To understand this, it is useful to have a little parenthesis on how information and knowledge is represented in our own brains.