A prepaid SIM card is a type of mobile phone card that allows users to pay for their phone service in advance. This means you can load a specific amount of money onto the card, which is then used for calls, texts, and data. Once the balance runs out, you can simply recharge it without being tied to a long-term contract. These SIM cards are popular among travelers and those who want to control their spending. They can be easily purchased from various retailers or online, and they often come with different plans to suit different needs, such as data packages or international calling options.