I had a copy of "The C Programming Language" by K&R. The title is a joke. It should read "The C Low Level Programming Language".
kent_dorfman766 already answered almost completely to that: C
is low level; well, the lowest level a HOL can be.
Today everbody starts 'high', and
maybe add assembler to their toolbox later. But fifty years ago it was often vice versa. So, you need to see it from the opposite point of view to better understand. If you come from assembler, only, and think of getting most basic data types, and control structures, so you don't have to create them everytime you need them over and over again, you will get to something pretty much like C.
By its nature come the pros and cons issues permanentely discussed today:
The more freedom a language provides, the more you can do with it, but the more effort is needed to create missing things, and the more you are on your own, and being responsible to create programs running safely.
(btw. I found an interesting article on HN yesterday:
There is no memory safety without thread safety)
But I like to add three things to the KR:
1. It almost completely covered the C language as it comes by default, and at ANSI standard in the time the book(s) were published.
2. The "KR" isn't meant to make the reader a systems developer, but to give a (very solid) introduction into the language with the aim to be used as an everyday tool for the common Unix-user: If you're missing a tool for a job to be done, write it yourself.
Today everybody looks for the proper tool to get a job done. Thirty...fifty years ago there weren't - by far - that many tools available. The idea was: Any user also has to have a bit of at least basic programming skills. Programming as kind of "configuring" your system. That's why the KR deals a lot with what users could use for their daily work: handling text, and files, etc.
3. The "KR" provides a solid foundation you can build on not only into C, but also into programming.
If you already are an at least a bit experienced programmer, and look at the exercises, you may think: "Ludicrous! This is kindergarten. To be done in most noobish programming classes!" At least I thought so.
Then I actually did the exercises (Not googling the results everytime you need to think of something. Really do it yourself! Completely.) Always only with what is known at the state according to the book's section. ("I want struct, and case!!" - No. Do it without it, if it wasn't part of the book, yet.)
Some of the excersise are really tough nuts to crack, as simply as they may look at the first glance.
You'll learn a lot - about C and programming.
It's a real solid class.
And as already said, it doesn't hurt to know a bit of C, even if you never going to program in it later, especially when you're dealing with unix[like] systems in my eyes a bit C basics are a must.
The KR provides a "solid license" to C, it's not a hacker's class.
And it's like driving cars:
The driving license only says your skill is sufficient enough to participate the public traffic on the road, it doesn't mean you are a good driver.
You have to drive
a lot - while using your brains - to actually become one.
)