Y-DNA follows your direct paternal line — father, his father, and so on. mtDNA (mitochondrial DNA) follows the direct maternal line — mother, her mother, and so on — and everyone inherits it, women and men alike. They trace two single, opposite threads of your family tree; neither is the same as an overall ancestry estimate, which blends all your lines.
What’s the difference between Y-DNA and mtDNA?
How Y-DNA traces your paternal line and mtDNA the maternal line — two opposite single threads of your tree.