You can find easily in textbooks that definitions for dominant and recessive alleles as follows:
Dominant allele: produces working protein and shows its effects in hybrid state.
Recessive allele: produces defective protein and remains suppressed in hybrid state.
But I have these confusion:
Defectiveness or benefit is relative thing.
There are many genetic diseases which are caused by dominant genes, for example short toe fingers. The protein related to it is also defective.
Another definition includes dominant as wild type most circulated while recessive as mutant allele. But even this seems to be unsatisfactory as every mutation cannot be recessive or defective.
Then, finally, what determines dominance of an allele over others?