White Hat SEO refers to the usage of SEO strategies, techniques and tactics that focus on a human audience opposed to search engines and completely follows search engine rules and policies Or any SEO tactic that maintains the integrity of your website and the SERPs (search engine results pages) is considered a "white-hat" search engine optimization tactic.
White-Hat SEO Tactics:
1. Quality Content
2. Use Structural (Semantic) Mark Up and Separate Content from Presentation
3. Titles and Meta Data
4. Keyword Research and Effective Keyword Use
5. Quality Inbound Links
And last but not the least keep them updating.