why was Othello so easily manipulated by Iago ?

why was Othello so easily manipulated by Iago ?

example how Othello was manipulated by Iago ? and what caused him to do that, and why he was successful with his plan ?

I will drop the link to the play article below

https://www.emcp.com/previews/AccessEditions/ACCESS%20EDITIONS/Othello.pdf