Can I use my old charging plug with a new iPhone or iPad?
You can't use an old USB-A charging plug with the cable supplied with a new iPhone or iPad. If you already have a USB-C Apple charging plug then you can certainly use that with any new Apple iPhone or iPad but many of us will still have the previous USB-A charging plugs. . Apple's old charging plugs, like most others, had a USB-A socket into which a USB-A to lightning cable could be inserted. Lightning is a proprietary Apple standard and is now replaced by USB-C, an international standard, on the latest iPads and iPhones. USB-C plugs and sockets are similarly sized to lightning plugs and sockets but are not compatible. USB-C is now being adopted as the universal standard and Apple supplies a cable with the latest iPhones and iPads that has USB-C plugs at boath ends. Apple still sells some older iPhone models which have lightning sockets but these are supplied with a cable that has a USB-C plug at one end and a lightning plug at the other. If you have bought a new iPhone with a lightning socket you can, of course, just continue to use your old charging plug and lightning cable and put the supplied USB-C to lightning cable to one side for now. Apple does not supply a charger with most of its devices now, just a cable. For use in conjunction wih the new cables, Apple sells a 20 Watt charger plug with a USB-C socket priced at £19. Apple describe this as a 20W USB-C Power Adapter. Apple also sells higher power chargers for faster charging. Investing in a new USB-C charger is your best solution since USB-A is being phased out rapidly by most manufacturers. An alternative which I considered and rejected is cheap adapters which allow you to continue to use your current charger; I found a 3-pack of USB-A to USB-C adapters on Amazon for about £6 but the reviews made it clear that many people found these to be useless. Another option is to purchase an Apple-certified USB-A to USB-C cable but this won't save much in view of the relatively low cost of Apple's 20 Watt charger. USB-A cables and chargers will soon be following other standards like SCART into obscurity; it's probably best just to move on. My advice is to purchase the new 20 Watt USB-C charging plug from Apple or one of the higher wattage chargers if you need faster charging.