Sharing huge files over the internet is quite a pain if you have limited bandwidth connection. Many users split large files into smaller parts and then share them on the Internet.
These large files can then be easily downloaded in parts and later rejoined to create the actual file.
Usually in many cases there might be several pieces of files called as filename.001, filename.002, filename.003 and so on. There may be any number of files but the extension will always be incremental so the next file in the above series may be .004 and so on.
In order to join the files you will require to download HJ-Split. HJ-Split is a portable software. Once you have downloaded it you can double click on the executable to launch it.
To join the .001 and other files in the series, select Join from the HJ-Split options and select the input file (this will always be the .001 file). Select the output directory and click on start to join the files into a single one.
After you have joined the files you can safely delete .00x files.