I’m tall when I’m young, and I’m short when I’m old. What am I?

What is always in front of you but can’t be seen?

What can you break, even if you never pick it up or touch it?

What goes up but never comes down?

I shave every day, but my beard stays the same. What am I?

What has many keys but can’t open a single lock?

What is black when it’s clean and white when it’s dirty?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?