“Term-frequency ⨉ Inverse Document Frequency”, or “tf-idf”, measures how important a word is to a document in a collection or corpus.

Spring Roo is a lightweight tool aimed at developer productivity. Via an intuitive command line interface it supports operations such as Java web project creation, persistence configuration and view scaffolding. Roo creates a Java web project that uses the Spring framework, and leverage some best well known practices in Java development such as dependency injection, aspect oriented programming, object/relational mapping (O/RM).

ExpressionEngine is a commercial content management system, written in PHP. Most ExpressionEngine questions will be better asked on the ExpressionEngine StackExchange, unless they involve development (such as developing extensions in PHP).

An Open Source MQTT v5/v3.1/v3.1.1 Broker

The web3.js library is a collection of modules which contain specific functionality for the ethereum ecosystem allowing to ease interactions with Ethereum blockchain, its smart-contracts and related encryption/decryption functions.

Use this tag for questions about PowerMockito, a Java Framework that allows the mocking of usually un-mockable types, i.e. statics, and private methods, in conjunction with the Mockito framework. Questions about using PowerMock with EasyMock should be tagged [powermock] instead.

Facebook Messenger is an instant messaging service and software application which provides text and voice communication. Integrated with Facebook's web-based Chat feature and built on the open-source MQTT protocol, Messenger lets Facebook users chat with friends both on mobile and on the main website. Information from : Wikipedia

for PostgreSQL questions specific to version 9.4

In telecommunications, loopback, or a loop, is a hardware or software method which feeds a received signal or data back to the sender.

In the C++ programming language, the delete operator calls the destructor of the given argument, and returns memory allocated by new back to the heap.

An Apple protocol, for model object representing a point on a map view