What are examples of ${{1}^{st}}$, ${{2}^{nd}}$, and ${{3}^{rd}}$ class levers?

Hint: The word machine has come from the Greek word which means to help make things easier. "Energy still remains conserved because machines can't do work more than the energy we put in. It helps to reduce the input force (Effort) to perform a job. Anything that reduces human effort is a machine. We are surrounded by different types of machines.

Complete step by step answer:
Now, What about the Lever.
The lever is not anything different, but it is a type of a rod and the things we encounter in day-to-day life having a rod-like function is "Lever."
Lever has one point fixed through which we can easily rotate it about that point.
Such as a bottle opener, scissors, pliers, stapler, nut-Cracker; etc.
There are three types of lever
${{1}^{st}}$ class lever
This is a kind of lever which has the fulcrum in between the load and also the force applied.
For example, scissors, seesaws, crowbars. Etc.
${{2}^{nd}}$ class lever
In this, the fulcrum is at one end and also the force applied is on the opposite end. the load is situated within the middle of those two.
For example: Wheelbarrow, Staplers, Doors or gates, Bottle openers etc.
${{3}^{rd}}$ class lever
These are the levers within which the fulcrum is at one end and also the force is applied in the middle and the weight is on the opposite end.
For example: Fishing rod, baseball bat, bow and arrow etc.

Note: Lever are used in machines, they are actually a part of machines and not a complete machine, the example state above is just to show that what object actually works on what kind of lever. They are really important in our life from very basic day to day usage to launching a spacecraft in space, they are used everywhere.