see e.g.
http://stackoverflow.com/a/1530193
https://msdn.microsoft.com/en-us/library/aa241721(v=vs.60).aspx

Cake.Net creates a tools folder at the root which contains downloaded packages and should not be checked in.

.jfm files have started blocking checking for .sqlproj projects in Visual Studio. .jfm files are a new file-type created by the Microsoft ESENT database engine - this is a recent improvement only in Windows 10 Anniversary update. As the SSDT .sqlproj type in Visual Studio uses this engine for .dbmdl metadata files, and this file is locked by the user, this currently blocks users from checking into Git repositories.

This fix helps mitigate this by avoiding checkin of this file type.

__pycache__/
*.pyc

I've just upgraded to ASP.NET Core RC2, and I've found that Visual
Studio is producing a file called project.fragment.lock.json. When I
delete the file it is recreated during build. Given project.lock.json is
already ignored this looks like another file to ignore.

Commit a25589c921 introduced an ignore line for ApplicationInsights.config. This change breaks builds on certain systems, namely VSTS.

The current ASP.NET 4 template adds ApplicationInsights.config to the project's .csproj file. When VSTS attempts to build the project, it will fail if it cannot find ApplicationInsights.config.

ApplicationInsights.config is a required application file and should not be ignored.

https://www.google.com/?gws_rd=ssl#q=_pkginfo.txt&nfpr=1

I found I have this file not being ignored and a quick search shows these files :/

Added bower_components to .gitignore

Windows Azure -> Microsoft Azure. Due to https://azure.microsoft.com/sv-se/blog/upcoming-name-change-for-windows-azure/

Ignore Azure ApplicationInsights.config in VisualStudio.gitignore

The authoring of NuGet packages quite often include `build` folders, and when this is .gitignore'd it's very often the source of bugs in files that don't get checked in.

I've never seen a Visual Studio project that builds to a `build` folder (`bin` is the default name). As this is a Visual Studio template file, and we have real projects that include `build` folders that include source code, I recommend we remove suppression of this folder.

StyleCop.Analyzers is the modern re-invention of StyleCop, and uses a StyleCop.json file that the default .gitignore file made very difficult to check in, and easy to think was checked in but isn't.
See 32057fff82/documentation/Configuration.md (source-control) for the documented case.

Looking through history, this line was last touched to make it case insensitive, and before that the line was in the original VisualStudio.gitignore file, without justification for why it should ignore all file extensions. From my experience with stylecop, the only file I remember it creating was stylecop.cache. I would change `[Ss]tyle[Cc]op.*` to `[Ss]tyle[Cc]op.cache` but there is already a line for suppressing all *.cache files (which wasn't there when the stylecop line was originally added). So I believe this line is now obsolete, and as I explain above, actually problematic.

Added extensions of new database engine for C++ (sqlite-based) from
Visual Studio 2015
(Tools - Options - Text Editor - C/C++ - Experimental - Enable New
Database Engine)

Recent versions of FAKE uses a cache folder containing a compiled version of all scripts named .fake that should never be commited to git.

Added ignore as recomended in http://fsprojects.github.io/Paket/getting-started.html

Ignoring directory "efc" and "rfc" created by the Windows Azure Emulator

Directory before starting emulator the first time:

Directory: C:\temp\AzureCloudService1\AzureCloudService1

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----         9/1/2015   9:16 AM                bin
d-----         9/1/2015   9:16 AM                WorkerRole1Content
-a----         9/1/2015   9:16 AM           3014 AzureCloudService1.ccproj
-a----         9/1/2015   9:16 AM            144 AzureCloudService1.ccproj.user
-a----         9/1/2015   9:16 AM            505 ServiceConfiguration.Cloud.cscfg
-a----         9/1/2015   9:16 AM            505 ServiceConfiguration.Local.cscfg
-a----         9/1/2015   9:16 AM            428 ServiceDefinition.csdef


And after starting the Emulator:

Directory: C:\temp\AzureCloudService1\AzureCloudService1

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----         9/1/2015   9:16 AM                bin
d-----         9/1/2015   9:19 AM                csx
d-----         9/1/2015   9:19 AM                ecf
d-----         9/1/2015   9:19 AM                obj
d-----         9/1/2015   9:19 AM                rcf
d-----         9/1/2015   9:16 AM                WorkerRole1Content
-a----         9/1/2015   9:16 AM           3014 AzureCloudService1.ccproj
-a----         9/1/2015   9:16 AM            144 AzureCloudService1.ccproj.user
-a----         9/1/2015   9:16 AM            505 ServiceConfiguration.Cloud.cscfg
-a----         9/1/2015   9:16 AM            505 ServiceConfiguration.Local.cscfg
-a----         9/1/2015   9:16 AM            428 ServiceDefinition.csdef

In Windows Phone 8 development each profiler session generates a new .sap file, which is automatically added to the root of the project. This is an XML manifest describing the detailed profiler logs created in the PerfLogs folder.

There are use cases where you have gulp/grunt tasks that create the static files of a project from bower_components, images, scripts folders.

As discussed in #1505

More Information
http://blogs.msdn.com/b/msbuild/archive/2008/02/11/what-s-up-with-xxx-sln-cache.aspx

ignore all files in Log/log folder

As of Visual Studio 2015 CTP5 the Roslyn cache and suo files are stored in a .vs/ directory.