I am confused about the meaning of markedness. From the Wikipedia page I read:

The dominant term is known as the 'unmarked' term and the other, secondary one is the 'marked' term. In other words, it is the characterization of a "normal" linguistic unit (i.e. the unmarked term) compared to the unit's possible "irregular" forms (i.e. the marked term).

1. I believe that "dominant" means more frequent, but is it dominant inside one language or considering all natural languages together?

2. In this context, is dominance assumed to stem from biological constraints (like some sounds are easier to produce than others) or is this not necessary for the definition of markedness?

3. What is the reason that unmarked terms are used at all? Are they thought to occur by chance in a language? Or is there a pattern or constraint that explains their existence?

I am confused about the meaning of markedness. From the Wikipedia page I read:

The dominant term is known as the 'unmarked' term and the other, secondary one is the 'marked' term. In other words, it is the characterization of a "normal" linguistic unit (i.e. the unmarked term) compared to the unit's possible "irregular" forms (i.e. the marked term).

I believe that "dominant" means more frequent, but is it dominant inside one language or considering all natural languages together?