Inessive case is a locative grammatical case. The inessive carries the basic meaning of "in": "talo" (house)-> "talossa" meaning "in the house" (Finnish), "majas" - "in the house" (Estonian), "házban" (ház =house)- "in the house" (Hungarian).
In Finnish typically formed by adding "ssa/ssä", in Estonian - "s" to the genitive stem.
In Hungarian suffix "ban/ben" is most commonly used for inessive, although many others, such as -on, -re, -en, and others are also used, especially with cities.
In the Finnish language, inessive is the first of the six locative cases which as their basic meaning correspond to locational (http://wiktionary.org/wiki/Locational) prepositions in English.
The other locative cases in Finnish are:
es:Caso inesivo
fr:Inessif
fi:Inessiivi