We have discussed the 5 main categories of digital keyboard but it is common for many parents to pick up a digital keyboard from the closest local electronic store or a toy store.
Many of these digital keyboards are sufficient to get small children started out on their hobby of piano playing. Even adults choose to go this way in order to avoid heavy expense right in the beginning of learning to play the piano. The one main reason they choose to go down this path is that they figure that they need time to actually figure out whether learning the piano is something that is going to stick. If the hobby progresses onto serious levels then you can always upgrade to purchasing a more serious digital keyboard. It is a similar case of reasoning with children as well. Sometimes parents are not sure whether the child will take 2 learning the piano enthusiastically and continue for some time in the future.
However, I must strongly point out here that purchasing a good quality instrument is essential to progressing along and learning piano well. A substandard digital keyboard will only take you so far and will not allow you to learn the piano as it is meant to be learned. For example, in order to learn the piano the way it is meant to be played, you need to have features in your digital keyboard like weighted action and touch sensitivity. Without touch sensitivity, the finer nuances of playing a piano are completely lost. One of the biggest advantages of piano as a musical instrument is that you can play sounds as softly and as loudly as required by the composition. This tonal quality is controlled by pressing the keys softly or hard. This is an essential technique learned and a digital keyboard that does not have this feature fails completely in this regard. Also the functions of the sustain pedal are important in playing the piano. The cheaper digital keyboard that you purchase from your or store or the electronics store may not have this capability. So if you see yourself or your child strongly progressing and doing well in learning the piano, do not wait too long to purchase that more efficient and professional digital keyboard. Otherwise you will fail to progress in learning the piano the way it is meant to be played.