It needs a lot of time to develop a soft. Programmers used to develop a soft behind closed doors. For a few programmers, it is difficult to develop it fast or to remove all the bugs. As the recent development of the Internet, we can download programs easily. So, programmers began to open the test edition of a program. Downloaders use it, tell programmers where they found bugs. There are some programs which downloaders can change them, if they open source files. For example, Linux is made from many people by these process. Freesofts are usually with bugs and some danger. But there are more convenience than them. 
     ZIP files are usually used for downloading. There is a sentence. Yes,No,Yes,No,Yes,No,Yes,No,Yes,No
How will you remember? For example, Yes is 1 and no is 0. 1,0,1,0,1,0,1,0,1,0 Is this still difficult to remember? How about seeing a (1,0) as a group. (1,0),(1,0),(1,0),(1,0),(1,0) We can say five groups of (1,0)s. Isn't it easy to remember? Archive softs are doing somekind of things like this.
     Bugs are mistakes, viruses are deliberately addicted paragraphs. How can we prevent from infection? First of all, using vaccine softs are effective for old viruses. Downloading from portal sites are useful; they are already virus scaned. Seeing support BBS is also usefu to know bugs. If they are already used from more than 100 people, they are maybe safe.
      Trojan wooden horse is the most dangerous thing. If a popular soft was a dangerous virus which we can't easily known its infection, we would be in serious situaton. There is a novel that the OS is a trojan wooden horse. How can we avoid them? 
     We propose that there should be a committee. We pay $10 to it a month and tell it what soft we download. The committee checks the soft and tell the danger and insure if any damage. Then we can benefit from the free soft with ease.