We already saw fluidPage() being used to set up the environment for other layout functions to work. But this function can also be used to build a UI from scratch, using the fluidRow() function. Using fluidRow() within fluidPage() allows you to implement the standard bootstrap grid layout, as described at w3schools.com/bootstrap/bootstrap_grid_system.asp. Essentially, the interface is built up row by row using the fluidRow() function. Each row can be divided into sections of arbitrary width using the column() function. The column function takes a numeric argument specifying how wide it should be. The total of all of these arguments in a given row should always be 12. So, for example, a row might consist of columns of width 3 and 9, and the following row, perhaps widths of 4, 4, and 4. In this case, a very simple implementation using fluidRow() might look like this:

ui = fluidPage(
  fluidRow(
    column(width = 4, 
      sliderInput("slider", "Slider", min = 1, max = 100, value = 50),
      textInput("text", "Text")),
    column(width = 8, 
      tableOutput("table")
    )
  )
)