The goal is to ensure quality for a period of time after you buy it. That can be several days to several weeks, depending on the item. For instance, milk, assuming proper refrigeration, should last five to seven days past its sell-by date before turning sour.
An autoencoder is a neural network that is trained in an unsupervised fashion. The goal of an autoencoder is to find a more compact representation of the data by learning an encoder, which transforms the data to their corresponding compact representation, and a decoder, which reconstructs the original data.
QR code (abbreviated from Quick Response Code) is the trademark for a type of matrix barcode (or two-dimensional barcode) first designed for the automotive industry in Japan. A barcode is a machine-readable optical label that contains information about the item to which it is attached. A QR code uses four standardized encoding modes (numeric, alphanumeric, byte/binary, and kanji) to efficiently store data; extensions may also be used. The QR code system became popular outside the automotive industry due to its fast readability and greater storage capacity compared to standard UPC barcodes.