Protected vs Real

Hi
I am reading a course about A+. in One slide which has title od
"Real(16-bit) and Protected (32-bit) Operation Mode" (please see
below)
My questions:
1) does the real mode mean DOS and protected me Windows? if yes why
they are named so??
2) Why Real mode can access 1Mb memory while protected can access 4Gb
3) Why the Protected Mode can not do direct access to the memory??

Thanks a lot for the help

quote
Real(16-bit) and Protected (32-bit) Operation Mode
+ Real Mode
- Single task
- 16-bit data path, 1Mb of memory
- Direct Access Memory

+ Protected Mode
- Multitasking
- 32-bit data path; at least 4Gb of memory address
- OS manages access to RAM and does not allow a program direct
acces to it
/quote