Difference between regasm.exe, regsvcs.exe and gacutil.exe

I have built a class library in C# .NET. Now, I would like to know when can I use each of the following .exes on my .dll ?
1) regasm.exe
2) regsvcs.exe
3) gacutil.exe

Answers

1) regasm.exe.For making dotnet assemblies to interact with any com objects
2) regsvcs.exeGenerates, registers, and installs a type library into a specified COM+ 1.0 application
3)gacutil.exe - used for putting shared assembly in GAC( global Assembly Cache- Place for shared assemblies to share among applications)