Credit cards, along with many identity cards and access cards, have a magnetic strip on their reverse side which contains information about the card and card holder. If this strip is demagnetized, the card will become useless in a card reader, regardless as to whether or not it is valid. A number of objects in daily life can demagnetize a card. If a card is handled with care, it should not become demagnetized, and if your card does get demagnetized, it will need to be replaced by the card provider.

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