Subbulakshmi DSumathi KIndirani K2020-08-242020-08-2420192005-4238https://www.ijitee.org/wp-content/uploads/papers/v8i10S/J104908810S19.pdfhttps://dspace.psgrkcw.com/handle/123456789/1012In this paper a new class of open sets in a topological space called η-open sets is defined and the inclusive relationship of this set with the other existing sets like semi open, pre-open, α-open, r-open sets are discussed. In addition to this the concept of η-interior, η-closure, η-boundary, η-exterior, η-derived, η-border, η-neighbourhood, η-dense, η-residual are also introducedenη-openη-closedη-interiorη-closureη-boundaryη-exteriorη-derivedη-borderη-neighbourhoodη-denseη-residualArticle