I guess that could be the first question you might have if you stumbled on
these web pages.
Let's first say that your familiar, everyday electron is a lepton. Electrons
are familar because their movement through your electronic devices is what
What are electrons like ?
For one thing, they all have the same amount of electrical charge. This
sounds familiar since we know that electricity can give things an electrical
charge which can sometimes zap us. Because they have a charge, they are
attracted to oppositely charged objects like protons, and become bound into
atoms which make up all the stuff around us like chocolate or computers.
More leptons like electrons
There are two more particles that are identical to electrons, but more
massive. These don't exist in our every day life because massive particles
are unstable and typically decay into particles which have less mass whenever
they can. These two particles are also leptons, one being called the "muon"
which has a mass 200 times more than an electron, and one called the "tau"
which has a mass 3500 times more than the electron.
More leptons not really like electrons
Each of the three charged leptons above has a rather silent partner called a
neutrino. These three neutrinos have no charge, and because they are rather
silent when it comes to trying to notice them, only recently have we really
learned that they have mass.