Gerund

A gerund is a verb used as a noun. 
In English, the gerund is formed by adding -ing to a verb root. It is identical in form to the present participle (ending in "-ing") and can behave as a verb within a clause (so that it may be modified by an adverb or have an object), but the clause as a whole (sometimes consisting of only one word, the gerund itself) acts as a noun within the larger sentence. For example: "Eating this cake is easy."
In "Eating this cake is easy", "eating this cake", although traditionally known as a phrase, is referred to as a non-finite clause in modern linguistics. "Eating" is the verb in the clause, while "this cake" is the object of the verb. "Eating this cake" acts as a noun phrase within the sentence as a whole, though; the subject of the sentence is the non-finite clause, specifically "eating".
Other examples of the gerund:
Not all nouns that are identical in form to the present participle are gerunds. The formal distinction is that a gerund is a "verbal" noun – a noun derived from a verb that retains verb characteristics, that functions "simultaneously" as a noun and a verb, while other nouns in the form of the present participle (ending in "-ing") are "de"verbal nouns, which function as common nouns, not as verbs at all. Compare:
Double nature of the gerund.
As the result of its origin and development, the gerund has nominal and verbal properties. The "nominal" characteristics of the gerund are as follows:
The "verbal" characteristics of the gerund include the following:
Verb patterns with the gerund.
Verbs that are often followed by a gerund include "admit, adore, anticipate, appreciate, avoid, carry on, consider, contemplate, delay, deny, describe, detest, dislike, enjoy, escape, fancy, feel, finish, give, hear, imagine, include, justify, listen to, mention, mind, miss, notice, observe, perceive, postpone, practice, quit, recall, report, resent, resume, risk, see, sense, sleep, stop, suggest, tolerate" and "watch".
Additionally, prepositions are often followed by a gerund.
For example: