Bold or Italic

When to Use Italic vs. Bold

One school of thought is that since italic and bold are both used to emphasize certain parts of a text block, you should only use one of them, at least within the same text block. Another school of thought is that italic should be used for mild emphasis, and bold for strong emphasis. Source

Rules

1. Bold or italic—think of them as mutually exclusive.
2. Use bold and italic as little as possible. They are tools for emphasis. But if everything is emphasized, then nothing is emphasized. Source