Can I rewrite this sentence "Many teenagers feel that social media and their smartphones are mandatory", by substitute "mandatory" with one of these words: compulsory or necessary or essential? Is the meaning the same? Thanks a lot.
While very similar in meaning, mandatory and compulsory have slightly different meanings than necessary and essential.
Mandatory and compulsory mean (or at least imply) that it is a requirement that will be enforced by some form of official agency, such as the government.
"Military service during World War 2 and the Vietnam war was compulsory in the United States."
"It is mandatory that students submit their high-school transcript as well as a recommendation from a teacher in order to be considered for the admittance to university."
Essential and necessary are usually used when something is needed as a matter of fact or circumstance.
"Food is a necessary part of life."
"Sauce is an essential part of pizza. Without it, you're really not making a pizza."
I think compulsory is the closest in meaning, but to me it has a sense that someone is explicitly saying "you must have this, you must use it". Like there's a formal rule in place, or someone is enforcing a requirement. Mandatory feels like the same level of pressure, but without the sense that it's a formal rule, more that it's "just the way things are".
(Mandatory can mean there's a formal requirement - it comes from mandate which is literally an order - but it sounds figurative here, whereas compulsory sounds more literal. To me anyway!)
Necessary and essential don't feel as strong, they lack the same sense of negative consequences. Necessary is stronger, but it still misses that "you have no option" tone. These feel more like strong recommendations, not warnings, if that makes sense?