What is 〜からです and when is it used? How does it differ from 〜ですから and 〜んです?


I have seen this expression a few times, and have never quite understood it.
In particular, it seems to be equatable both to ですから and to んです, but I can't
figure out where it would be used over either of those two expressions. Here
is an example I found on Google:

> 新聞{しんぶん}に目{め}を通{とお}していないと、仕事{しごと}が成立{せいりつ}しない **からです** 。

~~I believe this translates to "Since I haven't been skimming the newspaper, I
do not have a job." (but I am not sure, and please correct me if I'm wrong).~~

What does the からです mean in this sentence? And more importantly, when is it
appropriate to use, and how does it differ from ですから and んです?




> And more importantly, when is it appropriate to use,

Almost always, although it may sound a little bit informal. When asked "なぜ" or
"どうして", you'd answer with からです。

> なぜ遅れていますか？
>
> なぜなら、目覚まし時計が壊れていたからです。

(Why are you late? Because my alarm clock is broken)

> and how does it differ from ですから and んです?

ですから is a connective, not a final part. "Aですから、B". If there's no B coming
afterwards, then there's a problem. It's a bit like "since" in English. You
don't just say "Since I like ice cream," but you say "(B) I bought an ice
cream (A) since I like ice cream."

んです is "のです" used more colloquially. It's like からです, and (in "のです" form) more
formal. Also more common, as far as I can tell.




> And more importantly, when is it appropriate to use,

Almost always, although it may sound a little bit informal. When asked "なぜ" or
"どうして", you'd answer with からです。

> なぜ遅れていますか？
>
> なぜなら、目覚まし時計が壊れていたからです。

(Why are you late? Because my alarm clock is broken)

> and how does it differ from ですから and んです?

ですから is a connective, not a final part. "Aですから、B". If there's no B coming
afterwards, then there's a problem. It's a bit like "since" in English. You
don't just say "Since I like ice cream," but you say "(B) I bought an ice
cream (A) since I like ice cream."

んです is "のです" used more colloquially. It's like からです, and (in "のです" form) more
formal. Also more common, as far as I can tell.

