From this point on, any floppy diskette that that is put into the infected computer gets the virus code. A macro is a small program built into some data files to help the user automate tasks. Macros exist in certain applications, usually Microsoft Office files. MS Word, Excel, Access, and Power Point all have macros built into their programming. There are a few non-Microsoft applications that contain macros also, but it is mainly Microsoft Office.
Macro viruses are the only viruses that infect data files.
They can only infect data files that contain macro programs though. Since macro programs are executable the viruses are able to infect through them Macro viruses are becoming more prevalent. Data files are exchanged between computer users more than any other files. This makes it so macro viruses can replicate and spread more efficiently than other types of viruses. A network virus is a virus that is separated into several segments that each run on a different part of the network.