Does anyone know what this is

[saulsetton]

There is a blue dot by some of my contacts in samsung messages like this 

[Anonymous · Accepted solution]

That's rcs messaging

[saulsetton]

What is that

[Yamialex224]

It means it's basically imessage if they have it enabled you can see when they read it and when they are typing. It's also more secure than normal sms

[Anonymous]

That you can chat directly to them and see if they read your message