I copied this from wikipedia, very uncharacteristic because I’m not a fan of either wiki or copy/pasting. But through some random searches on the internet I came across this, it might be a nice intro to this catagory:
“thoughts are forms created in the mind , rather than the forms perceived through the five senses. Thought and thinking are processes by which these imaginary sense perceptions arise and are manipulated. Thinking allows beings to model the world and to represent it according to their objectives, plans, ends and desires”.