In California, categories of tangible personal property most significantly affected by sales tax regulations include:

1. Clothing and Apparel: Generally taxable unless specifically exempted.

2. Electronics: Items such as computers, smartphones, and home appliances are subject to sales tax.

3. Automobiles and Vehicles: Sales of new and used vehicles, parts, and repair services incur sales tax.

4. Furniture and Household Goods: Tax applies to items like furniture, kitchenware, and home decor.

5. Building Materials: Sales of construction and home improvement materials are taxed.

6. Sporting Goods: Includes bicycles, sports equipment, and exercise gear.

7. Computers and Software: Physical hardware and certain software are taxable, while SaaS is generally not.

8. Prepared Foods and Beverages: Sales at restaurants, cafes, and similar establishments are taxed.

9. Appliances and Electronics: Items such as refrigerators, washing machines, and televisions are taxed.

10. Digital Products: While digital goods are generally not taxed, if delivered on physical media or with ancillary services, they may become taxable.

These categories represent significant segments of consumer spending and business operations, making adherence to sales tax regulations crucial for both businesses and consumers in California.