There are various factors that make a PDF document lengthy compared to its source document. Rather than storing font sand image format in the application that opens it, it stores them in the document itself which increases the size of the file. PDF files take a lot of space in storing fonts in particular. This makes PDF files difficult to handle when used on the net. It is situations such as this that calls for downloading a PDF compression tool.
How PDF compression actually works
PDF file compression software is used to compress large PDF documents so that they may be conveniently used. Compression reduces the file size of the PDF documents significantly by removing redundant material. This is the basic task of PDF compression tools.
An example of compression is that of bitmaps. Bitmap images in a PDF documents take up lot of space. On the other hand, vector images are much smaller in size as they are only mathematical formulae that correspond to a set of data, and not actual data. PDF file compression softwares convert bitmaps into vectors wherever possible.
PDF file compressors can also extract sections of the source document text and create separate files out of them, which goes to reduce the size of the individual files. Despite the fact that the overall file size gets increased in this way, it proves useful for a user who does not need the whole file but only sections of it but still has to wait for the whole file to get downloaded.
Where PDF compression tools are available
You can easily find PDF compression tools at websites of software companies. These sites offer downloadable compressors, sometimes for free. Visit these sites and read and compare the features of the software that you need to download before you download it.