The particular arrangement of a material's atoms can be very advantageous for electric charge to travel through it. Metals, for instance, are very good conductors. Charges can flow through a metal with very little resistance. The particular arrangement of a material's atoms can by disadvantageous, however. Rubber, for instance, has its atoms arranged such that it is very difficult for electric charge to flow through it.
Rubber is considered to be an insulator.
A person's body acts as a conductor. Surprisingly, a person's body allows electric charge to travel through it easily. When certain types of materials are rubbed against other certain types, charge may be transferred from one to the other. Each object contains charge. For most objects, the number of negative charges equals the number of positive charges, giving a net charge of zero.