Here's a breakdown:
* Taxonomy: This is the science of classifying organisms into groups based on their shared characteristics. It's a hierarchical system, meaning organisms are grouped into progressively more inclusive categories (like species, genus, family, order, class, phylum, kingdom, domain).
* Observable structures: These are the physical features of an organism, such as its body shape, limbs, wings, scales, leaves, flowers, etc.
While modern taxonomy also incorporates genetic information, traditional taxonomy heavily relied on observable structures. This is why it's sometimes called morphological taxonomy.
Let me know if you'd like to learn more about taxonomy or morphological classification!