Gerunds are verb forms ending in "-ing" that function as nouns. They can serve as the subject of a sentence or appear after certain verbs or prepositions. Some examples of gerunds as subjects include "Trying local foods is a great way to learn about a culture" and "Volunteering is a rewarding way to spend a vacation." Gerunds can also follow verbs like "I enjoy traveling by bus" and "I dislike planning the travel details." Additionally, gerunds can come after prepositions such as "I am interested in joining a math course" and "I am concerned about protecting the environment."