According to Encyclopædia Britannica, a beta particle can have either a negative charge (if it is an electron) or a positive charge (a positron). Beta particles are emitted by unstable atomic nuclei. The emission of beta particles is called beta decay.
Radioactive particles are split into three groups: alpha, beta and gamma. These groups vary depending on size and energy levels. The alpha particle is comparatively large and does not have enough energy to penetrate even a sheet of paper. The beta particle, most often expressed as an electron, carries enough energy to penetrate human skin. Gamma particles, although massless, have extreme levels of energy and are dangerous to biological tissue.