Whats a binary droplet??

r/

For context I came across a scientific article called “Evaporation of ethanol-water sessile droplet of different compositions at an elevated substrate temperature” which mentioned ‘binary droplets,’ but when I tried to search up what they were all I kept getting was more articles that discuss them as though I am expected to know what they are (which in a sense I persume I am) so I was wondering if anyone could provide insight on what it is.

So far the closest thing I’ve gathered is that it’s a droplet of a certain volume and/or is made of 2 mixtures with different boiling points but to be fair I may be misunderstanding something, so any confirmation or clarification on what it is would be much appreciated 🙂