Yahoo organic
Organic search results come from indexing the web via Slurp, which recently migrated to the new domain at crawl.yahoo.net from inktomisearch.com. Yahoo provides organic and paid results to AllTheWeb and AltaVista.

Optimize your site for organic search visibility using traditional SEO tactics to ensure search-engine-friendly site structure, content and inbound links, emphasizing keyword-rich anchor text, meta tags, headers and body text. See Yahoo's Search Content Quality Guidelines for SEO tips. Suggest your site to Yahoo Search by submitting your web page(s), feed or mobile site to Yahoo for consideration to be included in the Yahoo Search index. For advanced organic search tactics, consider training for your in-house search marketing team.

Yahoo paid search
Yahoo provides several paid search advertising programs.

• Yahoo Search Marketing displays advertisers' pay-per-click (PPC) text ads on the SERPs with a title, description and URL. Advertisers pay per-click fees for this service.
• Yahoo Publisher Network displays advertisers' PPC text ads on sites within Yahoo's publisher network. Advertisers pay per-click fees for this service. All ads in YPN are served as traditional search listing type ads with a title, description and URL.
• Yahoo paid inclusion provides two options: Search Submit Express and Search Submit Pro for sites requiring fast spidering into the Yahoo index. These services incur annual inclusion and per-click fees.