1. Period after the abbreviation:
This is the traditional approach, and it's generally considered correct.
* Example: I live in CA.
2. No period after the abbreviation:
This is a more modern approach, and it's becoming increasingly common. It's especially popular in online writing and informal contexts.
* Example: I live in CA.
Important Note: The USPS (United States Postal Service) prefers using the abbreviations without periods.
Ultimately, the best approach depends on the context and your personal preference. If you're unsure, it's always safe to use a period after the abbreviation.
Here are some additional tips:
* Consistency is key: Use the same style throughout your document.
* Follow style guides: If you're writing for a specific organization or publication, follow their style guide.
* Check your audience: Consider your readers and the formality of your writing.