In a lecture I attended today, I heard the use of gerbs in the cobordism theory.

Previously, I use cobordism theory, but I never encounter the term "gerbs" when I work on bordism or cobordism group generators.

My understanding was that I can simply use characteristic classes, fiber bundles, topological invariants (Arf, ABK, $\eta$, etc.) etc to write down the cobordism invariants.

Why do we need gerbs in the cobordism theory? What are some good recommended lecture notes on this? Is this concept really helpful here? (Thanks so much for answering my naive inquiry.)

In a lecture I attended today, I heard the use of gerbes in the cobordism theory.

Previously, I use cobordism theory, but I never encounter the term "gerbes" when I work on bordism or cobordism group generators.

My understanding was that I can simply use characteristic classes, fiber bundles, topological invariants (Arf, ABK, $\eta$, etc.) etc to write down the cobordism invariants.

Why do we need gerbes in the cobordism theory? What are some good recommended lecture notes on this? Is this concept really helpful here? (Thanks so much for answering my naive inquiry.)