For many years, Apple used a 30-pin connection for their iPods and even the iPhone through the 4s models. When Apple introduced the iPhone 5 and iPad 4, a new cable came into play called the lightning cable. This is an 8-pin cable that is much smaller than the 30-pin and easier to connect and disconnect from the device.
Apple soon realized that a lot of third parties were making the Lightning Cable and some were so poorly made that they were damaging their devices. People were bringing in their devices for repair or replacement because they stopped working or had pieces of the poorly made connector stuck in their lightning port. So Apple introduced their certification program for third-party cables. Apple has set standards for quality and build and manufacturers need to follow them to be certified. Certified third-party accessories have the MFI logo on their packaging. MFI stands for Made for iPod, Made for iPhone or Made for iPad. If the cable is not made by Apple or MFI certified don’t buy it as it can wreck your device and cost you a lot more money than the few dollars you may have saved buying a non certified cable. You can read details about Apple’s MFI program here.
You can purchase a cable made by Apple and not have to worry or you can opt for one made by a third-party. I have used many cables from a multitude of companies and the cables made by an MFI certified third-party are as well made as those made by Apple. I have never had any issues with a lightning cable made by a certified third-party.
Put a little thought into how long you need that lightning cable to be. The most popular size seems to be one meter (about three feet) and I have found that in most cases, that length works fine although I had a few circumstances where I needed a two-meter (6 foot) length to reach a place that was further away than normal. No differences in performance for the longer distance was noticed.
The next part that you need to decide is where you wish to use it. Most purchase a secondary cable for use in the car as Apple provides an AC adapter with their iPhone purchase. I would recommend avoiding the car chargers that have the cable soldered into the DC adapter, especially avoid the ones that have a curly cable as they always pull your phone downwards toward the cable when in a mount. Hopefully your vehicle has a USB connection built-in, most sold over the past several years have at least one connection built into the car. Using the cable in this manner normally activates synchronization with your vehicle’s phone interface to sync up the contacts, most recent calls and songs.
Absence of a USB slot calls for purchase of a DC power adapter. Purchase an adapter that has at least two USB slots so your passenger can use it as well. Also be sure to get an adapter that will support at least 4.8 A so that two devices can share it at the same time. I don’t believe Apple certifies these adapters so purchase one that’s well made by a mainstream manufacturer.