.properties is a file extension for files mainly used in Java related technologies to store the configurable parameters of an application. They can also be used for storing strings for Internationalization and localization; these are known as Property Resource Bundles.

Each parameter is stored as a pair of strings, one storing the name of the parameter (called the key), and the other storing the value.

Format

Each line in a .properties file normally stores a single property. Several formats are possible for each line, including key=value, key = value, key:value, and key value. Note that single-quotes or double-quotes are considered part of the string. Trailing space is significant and presumed to be trimmed as required by the consumer.

Comment lines in .properties files are denoted by the number sign (#) or the exclamation mark (!) as the first non blank character, in which all remaining text on that line is ignored. The backwards slash is used to escape a character. An example of a properties file is provided below.

In the abstract, property is that which belongs to or with something, whether as an attribute or as a component of said thing. In the context of this article, property is one or more components (rather than attributes), whether physical or incorporeal, of a person's estate; or so belonging to, as in being owned by, a person or jointly a group of people or a legal entity like a corporation or even a society. (Given such meaning, the word property is uncountable, and as such, is not described with an indefinite article or as plural.) Depending on the nature of the property, an owner of property has the right to consume, alter, share, redefine, rent, mortgage, pawn, sell, exchange, transfer, give away or destroy it, or to exclude others from doing these things, as well as to perhaps abandon it; whereas regardless of the nature of the property, the owner thereof has the right to properly use it (as a durable, mean or factor, or whatever), or at the very least exclusively keep it.

In economics and political economy, there are three broad forms of property: private property, public property, and collective property (also called cooperative property).