Tort of Defamation mein kya hai, bhai?

Mujhe lagta hai kuch textbooks tort of defamation ke bare mein sahi tarah se explain nahi karte hain. Main seekhna chahta hoon clear example ke baare mein jisse iski vaste samaj aaye. Main sochta hoon ki defame karne wala koi bhi cheez hai - news article, tweet, post, ya phir koi public speech. Par kya hai yeh jo koi bhi cheez ko defame karna "libel" ya "slander" kyu hota hai? Aur kya hai yeh differes between both. Pls bataiye koi clear example.