- BL = Backlink
- CPC = Cost Per Click
- CSE = Comparison Shopping Engine or Custom Search Engine (Google)
- CSS = Cascading Style Sheet
- DC = Data Center
- DMOZ = Directory - Mozilla
- HTML = HyperText Markup Language
- IBL = Inbound Link
- LSA = Latent semantic analysis
- LSI = Latent Semantic Indexing
- OBL = Outbound Link
- ODP = Open Direcrory Project, See DMOZ
- OWBL = One way back link
- PPA = Pay Per Action
- PPC = Pay Per Click
- PR = PageRank (Google)
- RI = Regular index
- RSS = Really Simple Syndication, Rich Site Summary
- SE = Search Engine
- SEM = Search Engine Marketing
- SEO = Search Engine Optimisation
- SERP = Search Engine Results Page
- SI = Supplemental Index
- SSE = Yahoo! Search Submit Express
- SSP = Yahoo! Search Submit Pro
- SWL = SiteWide Link
- XML = Extensible Markup Language
Have I missed any other commonly used acronyms? Let me know, send me your comments.