This is probably the best, and definitely the most read tale by Johanna Spyri. This is also the original and only Heidi tale by the author, there are at least two other Heidi books, but these were not written by, or endorsed by Johanna Spyri.
I must admit that when I was little I did see an adaptation of this on tv, but it was always much more popular with my little sister, so seeing this was free, I thought why not give it a go. If you have never read this before, I should warn you that there is a strong Christian ethos at times in this tale, but not overbearingly so. Heidi is an orphan, and when her aunt gets the chance of a good job she leaves Heidi with her grandfather, a man living in isolation from the rest of the town, in the mountains. Living there, she makes friends with Peter the goatherd, and his family, and surprisingly lives an idyllic life.
When her aunt returns on the scene, it is to take Heidi away to Germany, where she wants to use her to advance her own position, but although making friends, Heidi yearns for the Alps. Full of little adventures and incidents, wherever Heidi goes she is bound to make friends. Getting into all kinds of scrapes, but not out of any mischeiviousness, this is a tale that still appeals to little girls especially, but it is still very readable for adults. If you haven't read this for ages, then why not try it again, and if you have never read it before like me, then you may find that you are easily immersed in the tale.