For anyone unfamiliar with Spanish naming customs, please know that it is not the same as it is in English; this is how our names work:
First name, Middle Name, Father's last name, Mother's last name.
Spanish naming customs are used by Hispanics, and in Hispanic countries, places where the official language is Spanish.
We all have two last names.* Our father's first last name, and our mother's first last name. When we are asked for our "full name" we write down four names.
Gabriela Loraine Arosemena Lachman
Normally, as in English naming customs, we abbreviate down to two names, and our middle name and mother's name get casually dropped.
Gabriela Arosemena. This usually happens for lack of space, time, or general convenience. Sorry mom.
A lot of the time, though, we don't like doing that because it feels unfair, and we sign three names.
Gabriela Arosemena Lachman
Octavio Méndez Lavergne
Loraine Lachman Varela
This is very normal and if you have Hispanic friends or live in one of our countries, you should see it a lot.
So... when you see three names for a Hispanic person, the name in the middle is not their middle name, it's their actual last name. You're seeing a first name and two last names, in that order.
A married woman's name would look as the following in such a scenario:
Loraine Lachman Varela de Arosemena
There is a specific thing which will tell you if she is married, which is the "de" ... there is no name dropping. A name is added. My name would be
Gabriela Arosemena Lachman de Méndez
...but it isn't, because I didn't do the paperwork.
The abbreviation of a married woman's name would be
Loraine de Arosemena
Loraine Lachman de Arosemena
...depending on a plethora of personal situations such as age/culture, people who will see the name written, pride on the name, wanting to be identified as belonging to a family or important relative, and so many more.
Most people have one middle name, though there are lots of people who do not have one.
Culturally, the middle name isn't really a thing, and most people only use their middle name when they sign their "full" four-word name, when their first name is very short or very common (such as Ana, or José), and also when they are being scolded...
In my case I just go by my nickname Gabi, and my scolding name is "Gabriela"... I use Loraine only for formal documents and also my screen name, Gabi Loraine.
I can go on. Ask me about names and feminism.
*of course, there are different kinds of families everywhere, we are not getting into that right now.