Safari doesn't open pdfs in browser, just downloads

Hello,

In my MacBook, I can not open pdf files on safari. Every time I want to read a pdf document on internet, I have to download it.

In the support section it is written that there is a build in pdf reader, but I can not find it.

Also, my internet plug ins folder is empty.

What should I do to read pdf files without downloading them? How can I use a pdf reader on my safari?

Thank you