Someone brought up a topic on a forum regarding homebrew being contaminated versus infected and which is the proper terminology. I figured it was worth a few minutes to provide my point of view on the topic. Often people will say something is infected when that may not be the case. I tend to think of a foreign object as contaminated. So if you find residue from a dirty bottle the beer may have been contaminated. On the other hand I tend to think of unwanted bacteria in the beer as an infection. So if you had a Lambic, it would be neither infected nor contaminated since that was what you were after in the first place. If you planned a nice Kolsch and it went off vinegar sour then you most likely have acetobacter which would be an infection. So IMO both terms are correct for describing beer. I use them often while judging, but I don’t use them interchangeably. If I tell someone to pay attention to their cleaning regimen then they probably had contamination, if I tell them to pay attention to their sanitation then their beer was probably infected.