This is something of a compendium of all of base R. The intent here is to provide explanations (in as simple a manner as possible) of how to use them. There are numerous examples and explanations of use cases, and (wherever possible) links to relevant articles and posts.

**.Call** – Modern Interfaces to C/C++ code

**.Device** – Lists of Open/Active Graphics Devices

**.Internal** – Call an Internal Function

**.Last.value** – Value of Last Evaluated Expression

**.Library** – Search Paths for Packages

**.Machine** – Numerical Characteristics of the Machine

**.Primitive** – Look Up a Primitive Function

**.bincode** – Bin a Numeric Vector

**.deparseOpts** – Options for Expression Deparsing

**.onLoad** – Hooks for Namespace Events

**.packages** – Listing of Packages

**.standard_regexps** – Miscellaneous Internal/Programming Utilities

**:** – Colon Operator

**::** – Double Colon and Triple Colon Operators

**Arithmetic** – Arithmetic Operators

**AsIs** – Inhibit Interpretation/Conversion of Objects

**Bessel** – Bessel Functions

**Comparison** – Relational Operators

**Constants** – Built-in Constants

**Control** – Control Flow

**Dates** – Date Class

**Defunct** – Marking Objects as Defunct

**Deprecated** – Marking Objects as Deprecated

**Encoding** – Read or Set the Declared Encodings for a Character Vector

**Filter** – Common Higher-Order Functions in Functional Programming Languages

**Foreign** – Foreign Function Interface

**ISOdatetime** – Date-time Conversion Functions from Numeric Representations

**Logic** – Logical Operators

**Memory** – Memory Available for Data Storage

**NA** – ‘Not Available’ / Missing Values

**NULL** – The Null Object

**NotYetImplemented** – Not Yet Implemented Functions and Unused Arguments

**Ops.Date** – Operators on the Date Class

**Paren** – Parentheses and Braces

**R.home** – Return the R Home Directory

**Random** – Random Number Generation

**Random.user** – User-supplied Random Number Generation

**Rdconv** – Utilities for Processing Rd Files

**Recall** – Recursive Calling

**Reserved** – Reserved Words in R

**Signals** – Interrupting Execution of R

**Special** – Special Functions of Mathematics

**Startup** – Initialization at Start of an R Session

**Syntax** – Operator Syntax and Precedence

**Sys.getenv** – Get Environment Variables

**Sys.getpid** – Get the Process ID of the R Session

**Sys.glob** – Wildcard Expansion on File Paths

**Sys.localeconv** – Find Details of the Numerical and Monetary Representations in the Current Locale

**Sys.readlink** – Read File Symbolic Links

**Sys.setenv** – Set or Unset Environment Variables

**Sys.sleep** – Suspend Execution for a Time Interval

**Sys.time** – Get Current Date and Time

**Sys.which** – Find Full Paths to Executables

**Trig** – Trigonometric Functions

**Vectorize** – Vectorize a Scalar Function

**abbreviate** – Abbreviate Strings

**abs** – Miscellaneous Mathematical Functions

**addTaskCallback** – Add or Remove a Top-Level Task Callback

**agrep** – Approximate String Matching (Fuzzy Matching)

**all** – Are All Values True?

**all.equal** – Test if Two Objects are (Nearly) Equal

**all.names** – Find All Names in an Expression

**any** – Are Some Values True?

**aperm** – Array Transposition

**append** – Vector Merging

**apply** – Apply Functions Over Array Margins

**args** – Argument List of a Function

**array** – Multi-way Arrays

**as.Date** – Date Conversion Functions to and from Character

**as.POSIXct** – Date-time Conversion Functions

**as.environment** – Coerce to an Environment Object

**as.function** – Convert Object to Function

**assign** – Assign a Value to a Name

**assignOps** – Assignment Operators

**attach** – Attach Set of R Objects to Search Path

**attachNamespace** – Loading and Unloading Name Spaces

**attr** – Object Attributes

**attributes** – Object Attribute Lists

**autoload** – On-demand Loading of Packages

**backsolve** – Solve an Upper or Lower Triangular System

**basename** – Manipulate File Paths

**bindenv** – Binding and Environment Locking, Active Bindings

**bitwNot** – Bitwise Logical Operations

**body** – Access to and Manipulation of the Body of a Function

**bquote** – Partial substitution in expressions

**browser** – Environment Browser

**browserText** – Functions to Retrieve Values Supplied by Calls to the Browser

**builtins** – Returns the Names of All Built-in Objects

**by** – Apply a Function to a Data Frame Split by Factors

**c** – Combine Values into a Vector or List

**call** – Function Calls

**callCC** – Call With Current Continuation

**capabilities** – Report Capabilities of this Build of R

**cat** – Concatenate and Print

**cbind** – Combine R Objects by Rows or Columns

**ceiling** – Rounding of Numbers

**char.expand** – Expand a String with Respect to a Target Table

**charToRaw** – Convert to or from Raw Vectors

**character** – Character Vectors

**charmatch** – Partial String Matching

**chartr** – Character Translation and Casefolding

**chol** – The Choleski Decomposition

**chol2inv** – Inverse from Choleski (or QR) Decomposition

**class** – Object Classes

**col** – Column Indexes

**commandArgs** – Extract Command Line Arguments

**complex** – Complex Vectors

**conditions** – Condition Handling and Recovery

**conflicts** – Search for Masked Objects on the Search Path

**connections** – Functions to Manipulate Connections

**contributors** – R Project Contributors

**copyright** – Copyrights of Files Used to Build R

**cosh** – Hyperbolic Functions

**crossprod** – Matrix Crossproduct

**cumsum** – Cumulative Sums, Products, and Extremes

**cut** – Convert Numeric to Factor

**cut.POSIXt** – Convert a Date or Date-Time Object to a Factor

**data.matrix** – Convert a Data Frame to a Numeric Matrix

**date** – System Date and Time

**debug** – Debug a Function

**deparse** – Expression Deparsing

**det** – Calculate the Determinant of a Matrix

**detach** – Detach Objects from the Search Path

**diag** – Matrix Diagonals

**diff** – Lagged Differences

**difftime** – Time Intervals

**dim** – Dimensions of an Object

**dimnames** – Dimnames of an Object

**dir.create** – Manipulaton of Directories and File Permissions

**do.call** – Execute a Function Call

**double** – Double-Precision Vectors

**dput** – Write an Object to a File or Recreate it

**dump** – Text Representations of R Objects

**duplicated** – Determine Duplicate Elements

**dyn.load** – Foreign Function Interface

**eapply** – Apply a Function Over Values in an Environment

**eigen** – Spectral Decomposition of a Matrix

**encodeString** – Encode Character Vector as for Printing

**eval** – Evaluate an (Unevaluated) Expression

**exists** – Is an Object Defined?

**expand.grid** – Create a Data Frame from All Combinations of Factors

**expression** – Unevaluated Expressions

**file.access** – Ascertain File Accessibility

**file.choose** – Choose a File Interactively

**file.path** – Construct Path to File

**file.show** – Display One or More Files

**files** – File Manipulation

**findInterval** – Find Interval Numbers or Indices

**force** – Force Evaluation of an Argument

**function** – Function Definition

**gc** – Garbage Collection

**gc.time** – Report Time Spent in Garbage Collection

**gctorture** – Torture Garbage Collector

**get** – Return the Value of a Named Object

**getHook** – Functions to Get and Set Hooks for Load, Attach, Detach, and Unload

**getLoadedDLLs** – Get DLLs Loaded in Current Session

**getNativeSymbolInfo** – Obtain a Description of one or more Native (C/Fortran) Symbols

**getTaskCallbackNames** – Query the Names of the Current Internal Top-Level Task Callbacks

**gettext** – Translate Text Messages

**getwd** – Get or Set Working Directory

**gl** – Generate Factor Levels

**grep** – Pattern Matching and Replacement

**grepRaw** – Pattern Matching for Raw Vectors

**groupGeneric** – S3 Group Generic Functions

**gzcon** – (De)compress I/O Through Connections

**hexmode** – Display Numbers in Hexadecimal

**iconv** – Convert Character Vector between Encodings

**identical** – Test Objects for Exact Equality

**identity** – Identity Function

**ifelse** – Conditional Element Selection

**integer** – Integer Vectors

**interaction** – Compute Factor Interactions

**interactive** – Is R Running Interactively?

**invisible** – Change the Print Mode to Invisible

**is.R** – Are we using R, rather than S?

**is.finite** – Finite, Infinite, and NaN Numbers

**is.function** – Is an Object of Type (Primitive) Function?

**is.language** – Is an Object a Language Object?

**is.object** – Is an Object ‘internally classed’?

**is.recursive** – Is an Object Atomic or Recursive?

**is.single** – Is an Object of Single Precision Type?

**is.unsorted** – Test if an Object is Not Sorted

**isS4** – Test for an S4 Object

**isSymmetric** – Test if a Matrix or other Object is Symmetric

**jitter** – ‘Jitter’ (Add Noise) to Numbers

**kappa** – Compute or Estimate the Condition Number of a Matrix

**kronecker** – Kronecker Products on Arrays

**labels** – Find Labels from Object

**lapply** – Apply a Function over a List or Vector

**length** – Length of an Object

**levels** – Levels Attributes

**library** – Loading/Attaching and Listing of Packages

**library.dynam** – Loading DLLs from Packages

**license** – The R License Terms

**list** – Lists - Generic and Dotted Pairs

**list.files** – List the Files in a Directory/Folder

**list2env** – From a List, Build or Add to an Environment

**load** – Reload Saved Datasets

**locales** – Query or Set Aspects of the Locale

**log** – Logarithms and Exponentials

**logical** – Logical Vectors

**lower.tri** – Lower and Upper Triangular Part of a Matrix

**ls** – List Objects

**make.names** – Make Syntactically Valid Names

**make.unique** – Make Character Strings Unique

**mapply** – Apply a Function to Multiple List or Vector Arguments

**mat.or.vec** – Create a Matrix or a Vector

**match** – Value Matching

**match.arg** – Argument Verification Using Partial Matching

**matmult** – Matrix Multiplication

**max** – Maxima and Minima

**max.col** – Find Maximum Position in Matrix

**mean** – Arithmetic Mean

**memCompress** – In-memory Compression and Decompression

**memory.profile** – Profile the Usage of Cons Cells

**merge** – Merge Two Data Frames

**message** – Diagnostic Messages

**mode** – The (Storage) Mode of an Object

**name** – Names and Symbols

**names** – The Names of an Object

**nargs** – The Number of Arguments to a Function

**nchar** – Count the Number of Characters (or Bytes or Width)

**nlevels** – The Number of Levels of a Factor

**noquote** – Class for ‘no quote’ Printing of Character Strings

**norm** – Compute the Norm of a Matrix

**nrow** – The Number of Rows/Columns of an Array

**numeric** – Numeric Vectors

**octmode** – Display Numbers in Octal

**on.exit** – Function Exit Code

**options** – Options Settings

**order** – Ordering Permutation

**outer** – Outer Product of Arrays

**parse** – Parse Expressions

**paste** – Concatenate Strings

**pmatch** – Partial String Matching

**polyroot** – Find Zeros of a Real or Complex Polynomial

**pos.to.env** – Convert Positions in the Search Path to Environments

**pretty** – Pretty Breakpoints

**print** – Print Values

**prmatrix** – Print Matrices, Old-style

**proc.time** – Running Time of R

**prod** – Product of Vector Elements

**prop.table** – Express Table Entries as Fraction of Marginal Table

**pushBack** – Push Text Back on to a Connection

**qr** – The QR Decomposition of a Matrix

**qr.X** – Reconstruct the Q, R, or X Matrices from a QR Object

**quit** – Terminate an R Session

**range** – Range of Values

**rank** – Sample Ranks

**rapply** – Recursively Apply a Function to a List

**raw** – Raw Vectors

**readBin** – Transfer Binary Data to and from Connections

**readChar** – Transfer Character Strings to and from Connections

**readLines** – Read Text Lines from a Connection

**readRDS** – Serialization Interface for Single Objects

**readRenviron** – Set Environment Variables from a File

**readline** – Read a Line from the Terminal

**regex** – Regular Expressions as used in R

**remove** – Remove Objects from a Specified Environment

**rep** – Replicate Elements of Vectors and Lists

**replace** – Replace Values in a Vector

**rev** – Reverse Elements

**rle** – Run Length Encoding

**round.POSIXt** – Round/Truncate Data-Time Objects

**row** – Row Indexes

**row.names** – Get and Set Row Names for Data Frames

**rownames** – Row and Column Names

**rowsum** – Give Column Sums of a Matrix or Data Frame, Based on a Grouping Variable

**sQuote** – Quote Text

**sample** – Random Samples and Permutations

**save** – Save R Objects

**scale** – Scaling and Centering of Matrix-like Objects

**scan** – Read Data Values

**search** – Give Search Path for R Objects

**seek** – Functions to Reposition Connections

**seq** – Sequence Generation

**seq.Date** – Generate Regular Sequences of Dates

**seq.POSIXt** – Generate Regular Sequences of Times

**sequence** – Create a Vector of Sequences

**serialize** – Simple Serialization Interface

**setTimeLimit** – Set CPU and/or Elapsed Time Limits

**shQuote** – Quote Strings for Use in OS Shells

**sign** – Sign Function

**sink** – Send R Output to a File

**slice.index** – Slice Indexes in an Array

**socketSelect** – Wait on Socket Connections

**solve** – Solve a System of Equations

**sort** – Sorting or Ordering Vectors

**source** – Read R Code from a File or a Connection

**split** – Divide into Groups and Reassemble

**srcfile** – References to Source Files

**stop** – Stop Function Execution

**stopifnot** – Ensure the Truth of R Expressions

**strptime** – Date-time Conversion Functions to and from Character

**strsplit** – Split the Elements of a Character Vector

**strtoi** – Convert Strings to Integers

**strtrim** – Trim Character Strings to Specified Display Widths

**structure** – Attribute Specification

**subset** – Subsetting Vectors, Matrices, and Data Frames

**substitute** – Substituting and Quoting Expressions

**substr** – Substrings of a Character Vector

**sum** – Sum of Vector Elements

**summary** – Object Summaries

**svd** – Singular Value Decomposition of a Matrix

**sweep** – Sweep out Array Summaries

**switch** – Select One of a List of Alternatives

**sys.parent** – Functions to Access the Function Call Stack

**sys.source** – Parse and Evaluate Expressions from a File

**system** – Invoke a System Command - 1

**system.file** – Find Names of R System Files

**system2** – Invoke a System Command - 2

**t** – Matrix Transpose

**table** – Cross Tabulation and Table Creation

**tabulate** – Tabulation for Vectors

**tapply** – Apply a Function Over a Ragged Array

**taskCallbackManager** – Create an R-level Task Callback Manager

**tempfile** – Create Names for Temporary Files

**tilde** – Tilde Operator

**toString** – Convert an R Object to a Character String

**topenv** – Top Level Environment

**trace** – Interactive Tracing and Debugging of Calls to a Function or Method

**traceback** – Print Call Stacks

**tracemem** – Trace Copying of Objects

**try** – Try an Expression Allowing Error Recovery

**typeof** – The Type of an Object

**union** – Set Operations

**unlink** – Delete Files and Directories

**unlist** – Flatten Lists

**unname** – Remove ‘names’ or ‘dimnames’

**utf8ToInt** – Convert to or from UTF-8-encoded Character Vectors

**warning** – Warning Messages

**warnings** – Print Warning Messages

**which** – Which indices are TRUE?

**which.min** – Where is the Min() or Max() or first TRUE or FALSE?

**with** – Evaluate an Expression in a Data Environment

**withVisible** – Return both a value and its visibility

**write** – Write Data to a File

**writeLines** – Write Lines to a Connection

**xtfrm** – Auxiliary Function for Sorting and Ranking

**zapsmall** – Rounding of Numbers