Identification
Identification is getting audience to see, feel believe and think what the writers themselves believe (Introduction to College Rhetoric and Inquiry (textbook), page 94). Getting the audience to identify with you (the rhetor) is often the key to persuading them to believe what you want them to believe.
Think about this: If we both believe the same things i.e. hold the same values, isn't is very likely that we're going to both agree on an issue? If you can put yourself into the rhetor's shoes, then you are more likely to understand and potentially relate to their point of view. And therefore, the rhetor has established themselves as a character you can relate to.
Ethos, pathos and logos are especially connected to identification.
In terms of ethos:
For the author/rhetor be viewed a credible, authoritative or have clear motives, as far as you're concerned, it means that your meaning of what is credible and authoritative aligns with theirs
As simply as possible, it means that if a doctor states a medical fact as true, and you believe them, it means your sense of authority includes seeing doctors as authoritative on health matters.
In terms of pathos:
For the rhetor to create a certain disposition, through the use of emotion, in you, you both have to hold the same sense of what the emotion means.
For example, if a rhetor told a story about about how they starved as children in order to persuade you to donate to hungry children, and you find the story to be one of injustice, one that makes you sad or disgusted at the system that made them hungry, then you both (rhetor and audience) have the same sense of what is unjust, sad and disgusting.
In terms of logos:
Reasonable ideas are usually only reasonable because you, as the audience, consider what the rhetor considers as reasonable, reasonable as well.