File extensions that begin with A.
Ext. Type of file
AA Audible audiobook
AAX Audible high quality
ABC This program's master index
ABK CorelDRAW auto backup
ABR Photoshop brushes
ACCDB Access database
ACL CorelDRAW keyboard accelerator
ACT FoxPro Action diagram
ACT Photoshop color table
AD After Dark image
ADM After Dark MultiModule
ADR After Dark Randomizer
AFM Adobe font metrics (Type 1)
AG4 Access G4 document imaging
AI Adobe Illustrator graphics
AI Encapsulated PostScript header
AIF Digital audio (Mac)
AIFC Digital audio (Mac)
ALB JASC Image Commander
AMR AMR Narrow-Band content
ANI Animated cursor
ANN Windows help annotations
ANS ANSI text
APE Monkey's Audio music file
APK Android application package
APP Mac application package
APP Various applications
ARC ARC, ARC+ compressed archive
ARJ Compressed archive (Jung)
ART Xara Studio drawing
ART AOL compressed bitmap
ASA ASP info
ASAX ASP.NET
ASC ASCII file
ASCX ASP.NET
ASD Word temporary document
ASF Windows streaming media
ASM Assembly source code
ASMX ASP.NET
ASP Active Server Page
ASPX ASP.NET
ASV Windows Media border
ASX Windows Media playlist
ATT AT&T Group IV fax
AU Digital audio (Sun)
AVI Microsoft movie format
AWB AMR Wide-Band content
AXD Actrix drawing
AZW Amazon Kindle e-book format
AZW3 Amazon Kindle e-book format