The space external to the outermost structure of a cell. For cells without external protective or external encapsulating structures this refers to space outside of the plasma membrane. This term covers the host cell environment outside an intracellular parasite.
Source:
GOC:go_curators
Comment
Note that this term is intended to annotate gene products that are not attached to the cell surface. For gene products from multicellular organisms which are secreted from a cell but retained within the organism (i.e. released into the interstitial fluid or blood), consider the cellular component term 'extracellular space ; GO:0005615'.