is this a simple sentence?

Firstly, Sometimes social media can be fun and entertaining to use, but excessive use of social media can lead to addiction.

No, this is not a simple sentence. It is a compound sentence as it contains two independent clauses joined by the coordinating conjunction "but."

Yes, "Firstly, Sometimes social media can be fun and entertaining to use, but excessive use of social media can lead to addiction" is a simple sentence.

Yes, the sentence "Firstly, Sometimes social media can be fun and entertaining to use, but excessive use of social media can lead to addiction" is a complex sentence. It contains multiple clauses and communicates multiple ideas.

To determine if a sentence is simple, compound, or complex, it can help to break down the sentence into its constituent parts. In this case, the sentence consists of two independent clauses: "Sometimes social media can be fun and entertaining to use" and "excessive use of social media can lead to addiction." These two clauses are joined by the coordinating conjunction "but."

Additionally, the first independent clause contains the adverb "firstly," indicating that it is part of a larger structure. This suggests that the sentence is more than just a simple statement.

Therefore, due to its multiple clauses and the use of coordinating conjunctions, the sentence is considered complex.