Are all apples edible?

[antipodes]

I don't have a garden for trees, but a friend has an apple tree. This year it is absolutely groaning with fruit, but she tells me that the fruit is not good, because it gets "worms" - they are not ripe yet, but I did pick one and nibbled it, and despite its unripeness, it seemed to me like it had potential (some people are very fussy about fruit - I even eat cherries that have worms, I just open them first!!!  ;D).
Now, I know nowt about apples, before coming to this country I had never seen an apple tree! Are all apples edible? Are some just nasty to eat? could these be cooking apples? cider apples?
The apples are quite small, the ones that are starting to ripen are red streaked and I would say they will have a yellowish-green background to them.
Basically I don't want her to throw them all out if there is a chance of using them in some way! To me, all apples must be edible but maybe I am wrong. Any thoughts? I should have taken a photo...

[antipodes]

[woodypecks]

Different varieties have different flavours ....some like them sweet , some like them sharp.....I tend to use the sharper varieties for Apple sauce ,jams ,jellys and pie fillers  ,where you would add sugar to taste .  Then there are the little tiny Crab Aples which some folk use for jellies to eat with game .   Someone with more knowledge will post in a minute I,m sure !  :)

[woodypecks]

..and yes  you are right , there are some varieties whose flavours are good for tasty cider too .

[goodlife]

I you have use for them..one way or other..yes..all apples are edible..that's if you mother-in-law don't think you are 'snow white'.. ;)

[Uncle_Filthster]

Simple answer: Yes, all are edible
Sweet are dessert apples, the more acidic ones are generally cooking or dual purpose and  some are even a bit bitter (cider apples).

[Alex133]

Most of mine get a worm in as don't spray them or anything, just cut them up before eating although they might add flavour if making cider  :)

[taurus]

I have a tree that as apples that are ideal for apple juice.  But as an eating apple there crap. Wish I new which varietie as its to small to be an cookery and to sweet for a cider.

[green lily]

The only poison in an apple is the seeds. They contain cyanide. Don't eat too many at once!