Intervals

An interval is "something from here to there". A part of something that we pick.
In mathematics, an interval, for example, an interval in a line of numbers, will represent a section of that line.

Intervals can be closed, open, or half-open. They are denoted by parentheses or brackets, with their respective starting and finishing points, called the endpoints.

A closed interval is an interval that is defined between those endpoints and includes the endpoints too. It is denoted by brackets:

An Open Interval is an interval that is defined between those same endpoints, but does not include the endpoints. In this case, the brackets face outwards. A half-open or half-closed interval is an interval that only includes one of the endpoints:!!!BE WARNED THAT INFINITIES CAN NEVER BE PART OF AN INTERVAL. IF YOU HAVE AN INFINITY AT EITHER PART OF AN INTERVAL, THAT PART WILL ALWAYS BE OPEN!

Example: You are now ready to learn about The Set of Natural Numbers N