Edited sentence: "Look and feel" lawsuits attempt to monopolize well-known command languages; some have succeeded.A patent normally covers the design of something with a function such as a machine or process.Copyright restricts the right to make and distribute copies of something written or recorded, such as a song or a book of recipes.Copyrights on command languages enforce gratuitous incompatibility, close opportunities for competition, and stifle incremental improvements.It is difficult and expensive to find out whether the techniques you consider using are patented; it is impossible to find out whether they will be patented in the future.Software has both these aspects - it embodies functional design in the algorithms and data structures it uses and it could also be considered as a recording which can be copied and "performed" (run).Software patents are even more dangerous; they make every design decision in the development of a program carry a risk of a lawsuit, with draconian pretrial seizure.The proper use of copyright is to prevent software piracy - unauthorised duplication of software.This is completely different from copying the idea behind the program in the same way that photocopying a book differs from writing another book on the same subject