Why can we have small fractions of a Bitcoin? I didn't study the inner workings of Bitcoin (yet), but already since when I just started using it, I wondered why a Bitcoin can be split up in parts.
Because there is a limit on the amount of Bitcoin that can be mined ever, fractioning Bitcoins is a huge advantage, especially if it's popularity increases.
Is there a limit on splitting Bitcoins into pieces?

EDIT:
I just found in this answer that BTC has a maximum of 8 decimals. Is it a good assumption then that every "BTC" consists of 10^8 smaller parts? So every block does not consist of 50 1-BTC parts, but 50*10^8 smaller parts?
Bitcoin amounts in the protocol and software are expressed as an integer number of "satoshis". 1 BTC is defined as 10^8 satoshis. So a block reward that is internally represented as 5*10^9 satoshis is displayed in the GUI as 50 BTC.

Splitting bitcoins to even smaller fractions will require a change in the protocol and software, and may be done when their value becomes much larger.