The chapter asserts that meanings are external and their loci are niches of semiotic artifacts, conceived as structured spaces that guarantee the stability of sign action. Semiotic artifacts are dynamically stabilized processes (signs-in-action), contrasting with the view of them as static material things. Meaning emerges from the action of these signs within their niche. The central thesis is that semiosis is niche construction: every sign action modifies the environment by updating the expectations and likelihoods for the production of future interpretants.