Answer:
The higher I climb, the hotter I engage. I cannot escape from my crystal cage.
You throw me out when you want to use me and you take me in when you don't want to use me. Who am I?
Once they sailed the sea, now they surf the web
We are five little objects of an everyday sort. You will find us all in a tennis court.
You throw away the outside, eat the inside, then throw away the inside. What is it?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?