What is convection current?

Convection current is the flow of hot fluid in a circular pattern.

A convection current is a form of transfer of energy. It occurs mainly in liquids, but it can also occur in gases. In a convection current, the particles with greater energy (the particles that are hotter) rise because they become less dense. As they rise, particles with less energy (cooler particles) rush in to replace the particles that rose as they are more dense. You can see this happening with sea and land breezes.