In real life, - you don't want to keep your children as teenagers, you want them to grow up and leave home at some point. With plants however, there are some that you want to keep in their teenage/juvenile form, as that is better behaved. (unlike real life)
In its Juvenile form, it is a great plant for covering walls and fences, - it is evergreen, grows in shade and lots of forms have very pretty leaves.
The adult form of Ivy has Larger leaves, and flowers and berries. The berries are loved as winter food by birds (although poinsonous to us and dogs), but the main problem if the ivy is in the wrong place is that the adult form grows a heavy wooden trunk.
Just 2 years later, this fence was in tatters
and had to be replaced at great expense. - The Ivy looked wonderful from the neighbours side,-A lovely big evergreen shrub that was shielding the fence from view.
So if you've got Hedera Helix - English Ivy in your garden, - give it a trim soon to keep it as a teenager before it becomes too heavy.