Conversation so far:
What are auxiliaries in marching bands?
Many marching bands have auxiliaries that add a visual component to the performance.
What kinds of visual components do auxilaries add to marching bands?
For ceremonial marching bands, visual components could be a traditional color guard or honor guard. For drum & bugle corps and corps-style field band, dance lines, majorettes.
Are there any other interesting aspects about the Marching band article?
Auxiliaries may perform as independent groups.

Question: Are they popular?
Self-contained rewrite: Are marching bands popular?