Interoperability of products such as computer memory and cell phones is achieved by industry standards that frequently incorporate patented inventions. When patent owners add their patents to standards, they agree to license these SEPs ("standard-essential patents") on FRAND ("fair, reasonable, and non-discriminatory") terms.
Owners of SEPs can have substantial market power, and royalty obligations can represent a substantial fraction of the costs of standardized products.
Damages for infringed SEPs require an investigation of FRAND requirements on top of the usual patent damages analysis. Litigation regarding SEPs can allege anti-competitive conduct by patent-holders.