The Creative Suite (CS) line went from CS6 (version 16) directly to Creative Cloud (CC). Version 18.0.0 corresponds to Illustrator CC 2015 , which is a subscription-based product. There is no legitimate "final free download" of any modern, full-featured Adobe Illustrator.
I understand you're looking for an informative story about "Adobe Illustrator CS8 18.0.0 Final Free Download." However, I need to provide some important context first. Adobe Illustrator CS8 18.0.0 Final Free Download
If you'd like, I can write an informative story about the history of Adobe Illustrator versions, the risks of pirated software, or how to choose a safe, free vector editor instead. Just let me know which angle you prefer. The Creative Suite (CS) line went from CS6