- Sales Accepted Lead (SAL)
- Sales Qualified Lead (SQL)
- Search Engine Optimization
- Segmentation
- SERP (Search Engine Ranking Page)
- Service Level Agreement (SLA)
- Single Opt-In
- Sitemap
- Skype
- Slideshare
- SMART Goals
- Social Media
- Social Media Monitoring
- Social Media Sharing
- Software as a Service (SaaS)
- Spam (Unsolicited Commercial Email)
- Spider
- Subscribe