R is a open source programming software for statistical computing and graphics. You can download and install R in any platform either it may be Windows, Mac or Linux. the free and official download of the software can be done in the following link https://cran.r-project.org/ .
Installed R then its always recommended to use a IDE for R. there are few good IDE for R most of them are open source and you can find it at no cost. My best choice and I hope most agree with me that RStudio is the best IDE for R programming. you can download the RStudio using the link : https://www.rstudio.com/
Pros of using R:
1. Suits for statistical analysis: The environment in R is well suited for statistical analysis and it does handle big data quiet fast and ease.
2. open source and cross platforms: R is open source and do work in cross platforms. regardless of any OS whether it may be in Windows, Mac or Linux(debian, redhat, suse, ubuntu).
3. add-ons: This is the important reason that I recommend using R. researcher around the globe develop and distribute the packages in CRAN (Comprehensive R Archive Network). two useful websites where you find addons are here:
these networks grow very fast and The packages number are increasing day by day.
4. Flexibility: Because R is programmed by users the package is very flexible and when you make use of the available scripts it will save you a huge time .
Con of using R
1.Minimal GUI: you cant simply say that R is completely command based. there are few GUI that makes analysis easy. (for ex: Rcmdr). people used to work with GUI will find it hard when the task is to be done in command based environment.
Over all I would say that for researchers who are interested in exploring the data will feel R as very helpful and It can help you to develop your ideas in to package and share it with CRAN which makes your research significant among the users.