what is a collagen peptide?

Biologically speaking, a collagen peptide is essentially a highly efficient delivery vehicle for specific amino acids.
When you ingest these short peptide chains, they don’t just get broken down entirely into single amino acids in the gut. Because of their unique structure (heavy in hydroxyproline, proline, and glycine), many of these di-peptides and tri-peptides cross the intestinal barrier intact. Once in the bloodstream, they act as signaling molecules to trigger our body’s own fibroblasts to produce new collagen.

Adding to Allen’s point, from a Quality Assurance perspective, the definition of a peptide comes down to its size, which we measure in Daltons (Da).
Regular gelatin (partially broken down collagen) has a molecular weight of around 50,000 to 100,000 Daltons. True high-quality hydrolyzed collagen peptides are usually tightly controlled to a molecular weight between 2,000 and 5,000 Daltons. When we receive a batch of raw material, testing that molecular weight is how we verify we actually got peptides and not just expensive gelatin.

Great foundational question. In nature, collagen is a massive, tightly wound triple-helix protein found in animal connective tissue—we call this “native collagen,” and it’s completely indigestible.
To create a collagen peptide, we put native collagen through a process called enzymatic hydrolysis. Specific food-grade enzymes are used to snip those long, rigid protein chains into tiny, extremely short chains of amino acids. These little fragments are the “peptides.” Because they are so small, they are highly water-soluble and bioactive.