What is an example of an ecological niche?

Archer Fish spitting at flying insects, using the air above water as a ecological niche.
A niche is a small category that’s made from splitting up large categories. For example, if you like Musicals, a niche genre would be Bollywood movies. Bollywood is a smaller part of Musicals.
When people talk of niches, they usually mean using an idea/place/product that no one else is using. For example, if you sell sweets in England, you might only sell indian-sweets which is a niche market that no one else is using.
Therefore, an ecological niche is an area used or inhabited by species that have adapted especially for it.
For example, Spitting fish (Archer Fish) spit out water to hit insects flying above the water’s surface.
The Archer fish is using the ecological niche of the ” air above water ” and has adapted to this niche by being able to spit water at flying insects.
Why do ecological niches exist?
The reason ecological niches exist is because it reduces competition. If lots of fish are already hunting in the water, the Archer Fish will have to fight them all to get food. However, because no fish is using the air above the water to hunt for flying insects, the Archer Fish adapted to use this niche and reduce competition.
Imagine a poor child who works on a garbage dump. If he wants to collect all the valuable electronic items, he will have a lot of competition. Instead, he might choose only to collect cloth which reduces his competition and makes it easier to work. He has made a niche by choosing a product that no one else is.