There are three types of Radiation: Alpha, Beta and Gamma. The activity of a substance is measured in Becquerals.
Alpha particles are Helium nuclei. They are positively charged and are a product of alpha decay
Beta particles are electrons that are the result of a neutron splitting into a proton and an electron, and are negatively charged.
Gamma comes in the form of waves, rather than particles. As a result, they have no charge.