I'm having trouble with understanding LESS and Bootstrap 3 work.

Hi, i'm extremely new to LESS and Bootstrap.

As i understand it, Bootstrap 3 is a CSS responsive framework.
LESS is alot of the commonly used CSS codes compiled in different files (variables for colors etc, layouts specifics, hovers) which come together when LESS is compiled to CSS.

I really don't understand the part where a div class is automatically assigned. For example, i tried searching for

div class="logo-text"

(I'm using T3_BS3_Blank), expecting it to be found in a php file where it would have been declared already, but could not!

I'm so confused at this point. So ok, "logo-text" was probably compiled from LESS to CSS, but how did logo-text know it was supposed to form a div for the logo title (Text Logo)? I would really like to understand this, if someone could please guide me.

I'm trying to create a banner position, did the whole blocks creation etc.... But then, how did the above logo-text thing happen? where is

div class="logo-text"

declared?