Content Pillar
One of a small number of recurring topics a person consistently publishes content about.
Content pillars are the three to five core topics someone builds their public content around, so that over time their audience associates them with those specific themes rather than a scattered mix of unrelated posts.
Example
A career coach might build content around three pillars: interview preparation, salary negotiation, and career pivots.
Nuance
Pillars work best when they're specific enough to be useful, not just broad categories like "business" or "leadership."