sometimes when you typeset a piece of text like poems, you actually want to go to the next line, so one solution would be to put a \par at the end of each line but if there are too much of these lines, then you will get sick of typing \par at the end of each line and so there is a CS namely \obeylines that does this automatically. Lets look at one example:

I am a Plain \TeX\ user,\par
and you are a Con\TeX t User,\par
There are other people who use La\TeX,\par
but we all are \TeX\ users.

{\obeylines
I am a Plain \TeX\ user,
and you are a Con\TeX t user.
There are other people who use La\TeX,
but we all are \TeX\ users.}

See in the above one, whenever I wanted to end the line and go to the next line, I had to put a \par, but in the second one I just put \obeylines which is the same that means ecah end of my lines will be treated like a \par.