What part of speech is "baking" in "baking is fun"? [duplicate]

In the sentence "baking is fun," what part of speech is "baking"?

Solution 1:

This is a gerund: a participle (a form of verb) being used as a noun.

Baking is fun

is strictly speaking ambiguous, though verb preferred.

Noun interpretation can be forced by adjectival premodification, as in "Occasional baking is fun."

You didn't ask but likewise with, for example, "I like baking": verb preferred but noun can't be ruled out.