Agile Methodology / Agile Methodologies
Agile methodologies are designed to break the software down into manageable parts that can be delivered earlier to the customer. The aim of any Agile project is to deliver a basic working product as quickly as possible and then to go through a process of continual improvement. An Agile project is characterized by having a large number of short delivery cycles (sprints) and priority is given to the feedback-loops from one cycle to the next. The feedback-loops drive continuous improvement and allow the issues that inevitably occur (including the way requirements have been defined or the quality of the solution provided) to be dealt with much earlier in the development life cycle. [Source]
Agile Testing including excellent resources on Agile Testing.