Update 9th January 2019:

From Bioc 3.8 (I believe), the new way to install Bioconductor base packages is like this:

if (!requireNamespace("BiocManager"))
    install.packages("BiocManager")
BiocManager::install()

Individual packages are then installed with:

BiocManager::install(c("GenomicFeatures", "AnnotationDbi"))
BiocManager::install(c("DESeq2"))

et cetera

[source: https://bioconductor.org/install/]

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Old post:

Hello and good evening wherever you are,

Bioconductor is not a package. It is a consortium / environment that maintains many R packages.

When you run R, you can 'connect' to the Bioconductor 'server' with:

source("https://bioconductor.org/biocLite.R")

...or:

source("http://bioconductor.org/biocLite.R")

After that, running biocLite() will update many fundamental R packages to their latest versions.

Running biocLite() with a package name as parameter will search for and install that package. For example:

biocLite("gplots")
biocLite("MASS")

You can then load the package's function into R via:

library(gplots)

...or:

require(gplots)

Packages can also be installed via CRAN with the install.packages() function, but CRAN does not seem to maintain their R packages as well as Bioconductor. On many occasions, CRAN will say that a particular package for your version of R does not exist, when it may already exist via Bioconductor.

Remember that Bioconductor is just a consortium. There are people behind that consortium who work hard to keep packages updated.

Kevin