In what contexts would I use 由? I know that 由 means through/via or from but I'm not sure exactly what contexts to use this in. For example the dictionary has this example sentence:

运输问题由他们解决。

I understand this but I would have used a sentence like these:


让他们解决运输的问题。

运输的问题是他们的责任。



I'm trying to get more familiar with when to use 由 and to incorporate it in my verbal interaction (otherwise I'll probably never use it and forget it). I realize the three sentences above are very close in meaning, but I'm not really sure how to understand when, where, and why I should use 由.
In your example '由' means 'by'. To give you more examples,

发动机是由蒸汽驱动的。
The engine is driven by steam.
这首歌是由歌手自己创作的。
The song is written by the singer himself.
小区里的足球场是由大家共同维护的。
The soccer field in the neighborhood is maintained by the community.