Here is the list of 19 reasons why a company needs a website, taken from the scientific article*:

1. Enhance company image/brand
2. Distribute product/company information
3. Identify new markets or customers
4. Generate sales leads
5. Gain an edge over competition
6. Improve communications with customers
7. Improve communications with channel partners
8. Improve communications with employees
9. Comply with requirements of a large customer or supplier
10. Sell products online
11. Improve marketing intelligence
12. Find information about new sources of supply
13. Find information on industry or other economic data
14. Reduce administrative costs
15. Reduce direct costs of creating product or service
16. Reduce shipping costs
17. Reduce advertising expenses for traditional media
18. Increase net profit
19. Provide or improve customer support

* Simha R. Magal, Parag Kosalge, Nancy M. Levenburg, (2009) “Using importance performance analysis to understand and guide e-business decision making in SMEs”, Journal of Enterprise Information Management, Vol. 22 Iss: 1/2, pp.137 – 151