SoftwareSerial Library not included with Arduino?

I’m trying to use the Software Serial library to interface with an ESP8266, but the library isn’t showing up in my list of installed libraries. I tried uninstalling and reinstalling the IDE, but it’s still not showing up.

So far, I’ve tried to compile using just the expression to include the SoftwareSerial library.

#include <SoftwareSerial.h>

This throws an error that says here is no such file or directory. I also tried installing and using NewSoftSerial:

#include <icrmacros.h>
#include <NewSoftSerial.h>

When I try to include that library, I get an error that says, “Serial has been moved into the Arduino core as of version 1.0. Use SoftwareSerial instead.”

Any fixes?