How many million species of all living things are described and given scientific names on earth?

On Earth, it is estimated that approximately 1.8 million species of all living things have been described and given scientific names.

It is important to note that this number is constantly changing as new species are discovered and described, and some previously thought-to-be distinct species may be reclassified as the same species based on new evidence. 

Nonetheless, the 1.8 million species that have been described and given scientific names represent a significant portion of Earth's diversity and provide important information about our planet's evolution and ecology.