In this paper, we study word regularities and in particular extensions of the notion of the word period: quasiperiodicity, covers and seeds. We present overviews of algorithms for computing the quasiperiodicity, the covers and the seeds of a given word. We also present an overview of an algorithm that finds maximal word factors with the above regularities. Finally, we show how Fine and Wilf's Theorem fails if we try to extend it directly to quasiperiodicity, as well as a new property on concatenation of periodic words.