Here's a breakdown:
* The first rudimentary microscopes: These were probably created in the late 16th century, possibly by Zacharias Janssen in the Netherlands. These early microscopes were simple magnifying lenses, not the complex instruments we have today.
* The first compound microscope: This is credited to Cornelis Drebbel around 1620. A compound microscope uses two or more lenses to magnify objects.
* The first microscope used for scientific discovery: This would be attributed to Antonie van Leeuwenhoek in the 17th century. He developed his own simple microscopes (much like a magnifying glass) and used them to make groundbreaking discoveries about microscopic organisms and blood cells.
So, depending on how you define "microscope," the answer could range from the late 16th century to the 17th century.
