The adbwinapi.dll is a very versatile command line tool. It allows you to communicate with a connected Android-powered device or an emulator. It is called an Android Debug Bridge that many refer to as an ADB.
Replace Your Missing File
Programmers and developers often use an ADB but the adbwinapi.dll file is most often searched for on Google because it is missing on a user's PC. Occasionally an error report appears saying that the adbwinapi.dll is missing. Most people do not know what it is so they Google it find it and add it back to where it is missing from. If you are one of those people then download the file and add it back. There is little more that a non-programmer can do with it. Try fixing your DLL error yourself by locating where the file should be and then replacing it. Try to fix it yourself before you try a DLL fixing program. Do not buy this because it is readily available online for free.
Conclusion - A Replacement File In Working Order
If you download the adbwinapi.dll you will receive a working file that may be used to communicate with an Android-powered device may be used to communicate and as an emulator or may simply be used to replace a missing file.