I couldn't grasp what it refers to exactly so I would like to understand how we use it:
from MLE, Score Vector is:
$$ S(\theta;y) = \frac{\partial l(\theta;y) }{\partial \theta} $$
$l$ comes from the log version of the likelihood function and this score vector has an asymptotic distribution with Information Matrix which is:
$$ I(\theta) = -E\left(\frac{\partial l(\theta;y) }{\partial \theta \partial \theta ^T } \right) $$
I appreciate it if you can explain how to use it and which sources I can use.