Electrons r tiny particles,possesing positive charge,presence of electrons can be observed through cathode ray tube experiment.

An electron is a negatively charged subatomic particle. It can be either free (not attached to any atom), or bound to the nucleus of an atom. we can see it by electronic microscope

Electron is a negative charge carrier in elctronics.we cannot see it.

The Electron is a fundamental subatomic particle that carries a negative electric charge. It is a spin- lepton that participates in electromagnetic interactions, and its mass is less than one thousandth of that of the smallest atom. Its electric charge is defined by convention to be negative, with a value of 1 in atomic units. Together with atomic nuclei, electrons make up atoms; their interaction with adjacent nuclei is the main cause of chemical bonding.