A high % of winemaking and beer making failures can be traced to lapse in cleaning and sterilisation.
Cleaning means removing visible dirt and residue from your equipment, sterilising means treating your equipment with a chemical that will eliminate or prevent the growth of spoilage organisms.
Everything that comes into contact with your wine or beer must be clean and properly sterilised. This means your fermenting vessel, but also syphon’s, airlocks, bungs, thermometers and hydrometers.