Manufactured food products and fresh produce have a shelf-life that tends to be governed by a range of intrinsic and extrinsic factors. Certainly, there are other factors at play, but the conditions within the food and the environment surrounding the food certainly play a major role. Here, Dr Philip Button provides an introduction to intrinsic and extrinsic factors that guide food food preservation, followed by a focus on how pH is related to food preservation and can be used to predict types of microbial growth and hence types of food spoilage.