为什么要用信用卡？这个问题的答案可以从多个方面进行解释。以下是对这个问题的解析以及英文翻译对照：

首先，信用卡是一种方便快捷的支付方式。使用信用卡可以避免携带大量现金的麻烦，同时可以在购物、旅行、住宿等方面享受方便快捷的支付体验。英文翻译为: Why use a credit card? The answer to this question can be explained from multiple perspectives. The following is an analysis of this question with English translation:

Firstly, a credit card is a convenient and efficient payment method. Using a credit card can avoid the trouble of carrying a large amount of cash, and also provide convenient and efficient payment experience in shopping, traveling, accommodation and other aspects.

其次，信用卡提供了额外的保障和保险。例如，信用卡可以提供一定的消费保障，如果购买的商品有问题，可以联系银行进行退款或赔偿。此外，信用卡还提供了一定的意外保险，例如航班延误、行李丢失等情况，可以获得相应的赔偿。英文翻译为: Secondly, credit cards provide additional security and insurance. For example, credit cards can provide certain consumer protection, such as refund or compensation if there is a problem with the purchased goods. In addition, credit cards also provide certain accident insurance, such as flight delay, lost luggage, etc., and can obtain corresponding compensation.

最后，使用信用卡可以积累积分和优惠券，享受更多的折扣和特权。许多信用卡提供积分奖励计划，使用积分可以兑换商品、服务或航空里程等。此外，信用卡还提供各种优惠券和折扣券，可以在购物、娱乐等方面享受更多折扣和特权。英文翻译为: Finally, using credit cards can accumulate points and coupons to enjoy more discounts and privileges. Many credit cards offer points reward programs, where points can be redeemed for merchandise, services, or airline miles, etc. In addition, credit cards also provide various coupons and discount coupons that can be used to enjoy more discounts and privileges in shopping, entertainment and other aspects.