Content pillars (or buckets) are 3–5 specific themes that your brand focuses on. They keep your content consistent, make planning easier, and help your audience know what to expect from you.
The themes should stay the same to maintain a consistent brand, but the format will change. For example, an "Educational" pillar could be a deep-dive blog post on your site and a quick "3 Tips" video on TikTok.
Review them every 90 days. Check your analytics to see which pillars are performing best against your primary goal and adjust your "mix" percentages accordingly.