The term integration refers to the ability to

Is simply the transfer of information from one type of program to another.

Integration is of the essentials tools that recent programs and softwares have. It pertains to the accessibility of the softwares to read and decipher a certain document from one type of software to another. This is useful when you have history datas that went back from 1990’s to today’s computer software since programs can reread this type of file. MS Word is one example that can understand the old file docs.