APK extension is used to deliver and install application software and middleware onto Google Android system. APK file contains compiled Android application code and all resources which are required by this code.

Office Open XML (also referred to as OOXML or Open XML) is an ISO/IEC standardized ZIP-compatible file format originally developed by Microsoft for representing spreadsheets, charts, presentations and word processing documents. Starting with Microsoft Office 2007, the Office Open XML file formats (ECMA-376) have become the default file format of Microsoft Office.

LNK files are commonly known as Windows shortcuts. They are used to refer to local files or remote urls. To view information in LNK file in Windows you can press right mouse button on a LNK file and select Properties from popup menu.

JNLP is short for Java Network Launching Protocol. This format is used by Java to download and launch applications over the network. JNLP applications typically don't run from user internet browser.

Files with extension DWG are usually used to store two and thre dimensional data used in engineering. Typical examples of software which use this format is Autocad, IntelliCAD, Caddie and Open Design Alliance applications. DWG is short for drawing. The .bak (drawing backup), .dws (drawing standards), .dwt (drawing template) and .sv$ (temporary automatic save) files are also DWG files.

CRDOWNLOAD is chrome partially downloaded file. Usually such file cannot be recovered since only part of it was downloaded. You need to visit website with download again and re-download it.

QFX file extension is a open financial exchange file generated by Quicken. It is used to store financial information. QFX files are based on XML format and usually contain financial transactions for certain accounts.

A dynamic-link library (DLL) is a module that contain functions and data that can be used by another module (application or DLL). A DLL can define two kinds of functions: exported and internal. The exported functions are intended to be called by other modules, as well as from within the DLL where they are defined. Internal functions are typically intended to be called only from within the DLL where they are defined. Although a DLL can export data, its data is generally used only by its functions. However, there is nothing to prevent another module from reading or writing that address.

File Extension OFX is an open financial interchange file format. It is used by financial instititutions to exchange information about financial transactions.