What is the correct and why to say?

[Makareena]

It was a great idea.
or
It is a great idea.

Which one is the correct and why , I’m trying to enhance my writing.
Thank you all : )
Please if you remark anything about my writing let me know.

[Ola.fun5]

I think both r correct ,but it depends ..
"It was a great idea" means that that idea had been suggested in the past.
"It is a great idea " means that the idea is just suggested and you approve the idea .

e.g.1- A. why didn't you like his idea?!!
B.It was great but it was impossible to be achieved.

e.g.2- A. what about going to Hollywood cinema !!
B. that's a great idea .
I'm not really sure ,but that's what I think ...

[Olcha]

I support Ola.fun5's opinion. Both variants are possible and their usage depends on the context and the time when the mentioned idea was proposed.

[Manushak]

Thank you so much

[Manushak]

I'm Manushak. My short name is Mane
I'm 26 years old.
I'm from Armenia.
I'm databases and reporting manager.
I'm not married yet.
I'm not tall.
I'm interested in learning English.

[moonlight1238@yahoo.com]

good day everybody,