R is the statistical environment. In was created as a freeware analog of commercial S-Plus which is in turn was implementation of the S language concept. The S language was first created in 1976 in Bell Labs, and its name was inspired by famous C language (from same Bell Labs). S-Plus started in the end of 1980s, and as many statistical software, was seriously expensive. In August 1993, two New Zealand scientists, Robert Gentleman and Ross Ihaka, decided to make R(this name was, in turn, inspired by S). The idea was to make independent realization of S language concept which would differ from S-Plus in some details (for example, in the way it works with local and global variables).
Practically, R is not an imitation of S-Plus but the new “branch” in the family of S software. In 1990s, R was developing slowly, but when users finally realized its truly amazing opportunities (like the system of R extensions—packages, or libraries) and started to migrate from other statistical systems, R started to grow exponentially. Now, there are thousands of R packages, and R is used almost everywhere! Without any exaggeration, R is now the most important software tool for data analysis.