In computer programming, a data type (or datatype) is a classification identifying one of various types of data, such as floating-point, integer, or Boolean, stating the possible values for that type, the operations that can be done on that type, and the way the values of that type are stored

Almost all programming languages explicitly include the notion of data type, though different languages may use different terminology. Common data types may include:

• integers,
• booleans,
• characters,
• floating-point numbers (decimals), and
• alphanumeric strings.

Work With the Files

A computer file is a block of information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage

Compression
Compression is the coding of data to save storage space or transmission time. Although data is already coded in digital form for computer processing, it can often be coded more efficiently (using fewer bits). There are many compression algorithms and utilities. Compressed data must be decompressed before it can be used.
Other compression utilties include zip, PKZIP, Stuffit and WinZip.

Conversion

There are a number of software applications that can be used to analyze a data file. Often, user A will create a data file in a format specific to software application 1 and user B needs it formatted for application 2. As a result, a market has appeared for still other software applications that can do the conversion from 1 to 2. The link above goes to a list of coversion tools.


Transferring

File transfer is the movement of one or more files from one location to another. A collection of electronically-stored files can be moved by physically moving the electronic storage medium, such as a computer diskette, hard disk, or compact disk from one place to another or by sending the files over a telecommunications medium. On the Internet, the File Transfer Protocol (FTP) is a common way to transfer a single file or a relatively small number of files from one computer to another.

 "Download" and "upload" are commonly used to denote file transfer as well as "ftp" (used as a noun and verb) even though these are technically not interchangeable terms.


File Extension

A filename extension is a suffix to the name of a computer file applied to indicate the encoding convention (file format) of its contents.

Text Files
.doc    Microsoft Word Document
.docx    Microsoft Word Open XML Document
.log    Log File
.msg    Outlook Mail Message
.pages    Pages Document
.rtf    Rich Text Format File
.txt    Plain Text File
.wpd    WordPerfect Document
.wps    Microsoft Works Word Processor Document

Data Files
.blg    Windows Binary Performance Log File
.csv    Comma Separated Values File
.dat    Data File
.efx    eFax Document
.pps    PowerPoint Slide Show
.ppt    PowerPoint Presentation
.pptx    PowerPoint Open XML Presentation
.sdf    Standard Data File
.vcf    vCard File
.xml    XML File

Audio Files
.aac    Advanced Audio Coding File
.aif    Audio Interchange File Format
.iff    Interchange File Format
.mp3    MP3 Audio File
.mpa    MPEG-2 Audio File
.ra    Real Audio File
.wav    WAVE Audio File
.wma    Windows Media Audio File

Video Files
.3g2    3GPP2 Multimedia File
.3gp    3GPP Multimedia File
.asf    Advanced Systems Format File
.asx    Microsoft ASF Redirector File
.avi    Audio Video Interleave File
.flv    Flash Video File
.mov    Apple QuickTime Movie
.mp4    MPEG-4 Video File
.mpg    MPEG Video File
.rm    Real Media File
.swf    Flash Movie
.vob    DVD Video Object File
.wmv    Windows Media Video File

Raster Image Files
.bmp    Bitmap Image File
.gif    Graphical Interchange Format File
.jpg    JPEG Image File
.png    Portable Network Graphic
.psd    Adobe Photoshop Document
.pspimage    PaintShop Photo Pro Image
.thm    Thumbnail Image File
.tif    Tagged Image File
.yuv    YUV Encoded Image File