How is current formed in conductors?

(N/A) When conductors are subjected to an electric field,the electric charges within them experience a force.
If these charges are free to move,they will constitute an electric current.
In atoms and molecules,electrons are bound to the nucleus by Coulombic forces. However,in bulk matter,molecules are packed so closely that the outer electrons are no longer strictly attached to a single nucleus.
In metals,some electrons are practically free to move randomly throughout the bulk material. When an external electric field is applied,these free electrons experience a net force and drift,resulting in an electric current.
In solid conductors,current is formed due to the motion of electrons.
In liquids (electrolytes),current is produced due to the motion of positive and negative ions in mutually opposite directions.
In gases,current is produced due to the motion of ions formed by ionization.