From everything I've been told by experts in the area, you should preserve your digital images in at least two different formats.
Even archival DVDs can fail or degrade over time, albeit a fairly long time. The ones I have are "guaranteed" for 40 years.
External, solid-state hard drives offer another option. They can hold massive amounts of digital images and offer one of the best forms of protection, but they are not completely immune to failure. Reading reviews on Amazon can give you an idea of the ones that perform best.
Flash drives are another method, but they are easy to lose, so be sure to label them and keep them in a safe space. They can also become corrupted. There are some special flash drives on the market just for photo organizing. One is called Picture Keeper. I've purchased one but have not used it yet, so I can't tell you how well it performs.
I'm not a big fan of storing my images on the cloud for privacy reasons. We have our digital images stored on computers and phones with backups on archival DVDs and flash drives. We also have a solid-state external hard drive that I haven't used yet but plan to transfer all of the images there soon.
We also make real copies of the photos we really love and put those in albums or frames.
I feel like having these back ups in different forms makes it more likely that if one fails, we will have the images in one of the other formats.