There's quite a lot, the easiest way to figure this one out is to look it up.
Answer:
Lol i had learned it but i forgot sorry
A simple sentence consists of only one clause. A compound sentence consists of two or more independent clauses. A complex sentence has at least one independent clause plus at least one dependent clause. A set of words with no independent clause may be an incomplete sentence, also called a sentence fragment.
No
This is a complex sentence. The sentence has two parts, a dependence clause and an independent clause. The dependent clause is "Especially after a rainstorm" and the independent clause is "Santa's Little Helper likes to sit in his porch swing and think." If this sentence was only made up of a dependent clause, then it would be a fragment.