Once the chart with its trend line is shown, we are in a position to establish whether there is a correlation or not between the two studied variables.

Negative and perfect correlation. Functional dependence. The cloud points are aligned.	r =-1
Negative correlation is stronger as it gets closer to -1 and weaker when it approaches to 0. Random dependence.	-1<r<0
Uncorrelated variables. There is no relation between variables. Random independence.	r=0
Positive correlation is stronger the closer it gets to 1 and weaker the closer it gets to 0. Random dependence.	0<r<1
Positive and perfect correlation. Functional dependence. The cloud points are aligned.	r=1

External resources: https://www.khanacademy.org/math/probability/regression (EN)