Emails are not files, so they do not have extensions.
The file extension of Windows mail is .eml
A file tree is extention to a file that branches out
The file extention is just .jpg The 128 x 96 is just a file size - it is NOT part of the extention.
A file extention isn't needed but when your the file has a file extention the computer can easily find the appropiate program to run it. If a file doesnt have a file extension the computer will require you to find the appropiate program with means more work for you to do
Peru
You're computer is regonising a file as an "Unknown File" only because it has no understanding of that file extention. Right click the file and select "Properties", find the extention name (Eg, .exe) and search for software that will read that extention name. If you're having further problems consult someone on a Technical Help Forum.
File Extention
common guys the answer for .dat is videos
*.txt. In reality the ascii file can have any extention. A ASCII file is just a raw text file with no enbedded codes within the file.
A console is saved in a file with an .msc file extention, and a snap-in in a console can itself be a console.
An Adobe Premiere video editing project file would usually have a .ppj extension.
Your question is very vague/ not clear, when you click on a file / picture, video, email, or any related file they all have one thing in common they all have a file extention as in WORD.EXE . When you click on the word progran it will open word and any other parts of the progran reguired in order for you to use the program. Same with opening a video file , it might have a mpg, mov, avi, or like extention but all are video related extentions. You can't play an AVI video using a MOV program , each program uses it's own set of rules running a program as in Apples quicktime opens AVI video files and Outletlook express opens/ starts the Email program. By the way you can rename almost ANY file to whatever you want as long as you LEAVE THE 3 letter extention the same. you can name a file 000 if you don't change the extention. Try and be more clear in what your asking. chet2010 chet is a idiot dont listen to him he has no idea what the event viewer is for basically to simplify this answer the event veiw shows 4 of the 5 W's tells WHO is in WHAT they are accessing WHEN then are accessing it and WHERE they accessed it from
It may have any extention. .exe ,.rar, .xls ,.mp4 etc