Many children have access to smart phones and iPads at a very young age. They know how to flip through a picture album, shrink, zoom, and probably delete.
Common Sense Media is a fantastic resource for age appropriate apps. There are apps for learning colors, numbers, patterns, puzzles, math, spelling, that are free, cheap, and well-rated. I highly recommend finding some that are specific to your child's development stage. Spend some time with them, letting them show you how the game is played, and give a little help if they need it.
Cautions: Some apps have ads on the screen that may be accidentally tapped, sending your toddler off onto some content that may not be ideal or offer purchase power.
It's not essential that you have a smart device your toddler can use, but it's also not essential that your toddler knows their ABC's until kindergarten. I strongly believe that mobile devices are essential tools, and there are smart ways to introduce them.