Recently someone on a forum asked about using bread yeast. Since that’s such a common question, I decided to record my answer here.
Generally speaking, you want the yeasts intended for wine, beer, or cider, or the occasional rare variety intended for mead, not for bread. These have been bred (no pun intended) to have a particular level of alcohol tolerance (though that is only a rough guide), temperature tolerance, production of esters, and other characteristics often important in brewing. Bread yeast has mainly been bred to have a given level of CO2 production, as that’s what makes bread rise. To us, that’s just a byproduct, usually to be gotten rid of (unless we’re trying to make it sparkling).
That said, it’s certainly possible to make a decent mead with bread yeast, and there are recipes that call for it – but you’ll get a much more consistent, and usually better, mead with yeasts intended for brewing.