When is a Verb not a Verb?

The answer is: when that verb is really a noun.
How is that possible? In English there are two ways to make this happen.
a. By using the infinitive form ot the verb (to go, to drink , to underestimate are some examples of verbs in infinitive form).
To think of defeat is unthinkable.
To give in before desperation is just the wrong way to go.
b. By using gerunds. A gerund is a verb using the ing form and is therefore a noun. For all intents and purposes a gerund has all the functions a noun has: it can be the subject of a sentence or it can an object and it can even be the name of something.
Working can be a glorious a deed or a great bore.
Jennifer hates waiting and prefers to be waited instead.
Swimming is the best thing to do if you want exercise.
We know Swimming as the name of that skill that allows us to move about in the water. Is there another name for that?
In order not to confuse Gerunds with the verbs plus ing used in the Continuous tenses we must use the context given.
Smoking is perhaps the most dangerous habit.
(Here Smoking is the subject of this sentence. It is a Gerund)
I was smoking and reading the paper when the alarm rang.
(Smoking, and also Reading, are the verb form of this sentence in the Past Continuous)
The verb plus ing in this case is not called a Gerund. The correct term is Present Participle.
In Spanish we don´t have a choice and use the Infinitive form of the verb only.