The hiragana syllable ね(ne). Its equivalent in katakana is ネ(ne). It is the twenty-fourth syllable in the gojūon order; its position is な行え段(na-gyō e-dan, “row na, section e”).
Sense 1 is used at such a frequency that it is often absent in a normal English translation, instead expressed with general inflection of voice, or context. It can also imply agreement. A common usage of it is in conjunction with particle さ(sa), as よね(yo ne).
Sense 3 is similar to filler particle さ(sa) in usage and placement, but is different in that it sounds more gentle, and also can be used in more polite situations (e.g. the common filler usage of ですね(desu ne), where です(desu) becomes part of the filler particle, and ignores its own grammatical meaning and usual syntax).