New learning.
I just noticed this in the advertising section of the forum.
The Bitcoin software, network, and concept is called "Bitcoin" with a capitalized "B". Bitcoin currency units are called "bitcoins" with a lowercase "b" -- this is often abbreviated BTC.
Image:
http://prntscr.com/mblnlfMeaning when I am paying someone in
Bitcoin then I am sending him
bitcoins 
We are
Bitcoiners and
bitcoins are our currency.
Thank you.
Yes you are right. I myself got to know about this fact about 3-5 months ago. The article I read differentiated it as
Bitcoin being a software/technology and
bitcoin as an asset/currency.
Example: I have 1
bitcoin in my
Bitcoin wallet. (Not true, but I wish it was true

)
Thanks for the info, I never gave it much thought! I'll try to follow the rule from now on. However, I think that we can write "bitcoin" as well, it's not always plural. For example, I received 1 bitcoin from a friend before, not Bitcoin, right?
I am also wondering whether we have to write the abbreviation only with capitalized letters (BTC, not btc) or it does not matter. And another thing is whether similar is true for other names of cryptocurrencies. While it seems logical that this should hold for LTC, for instance, I am not sure about Ethereum. We don't even use it in plural, right? "ethereums" sounds too weird to be right.
Any abbreviations should always be mentioned in capitalized letters. Example: I have sent him 1 BTC and not 1 btc. The same rule applies to all the cryptocurrencies.
While I am not sure about the plural thing but according to me we should be using the plural term only when the amount is greater than 1.
Example: I sent you 1.5
bitcoins. You sent me 0.5
bitcoin