The "Tip of the day" Thing?

Lets say that this is the hierarchy or an object you are trying to find:

Workspace

Model

Banana

Normally to find the object Banana you would have to create a recursive function to search workspace. When the second argument is true FindFirstChild will recursively search the directory until it finds the object.

Workspace:FindFirstChild("Banana",true) --Would return Banana
Workspace:FindFirstChild("Banana") --Would not find Banana

The equivalent recursive function.

function Recurse(Location,Name)
    for _,n in pairs(Location:GetChildren()) do
        if n.Name == Name then
            return n
        end
        Recurse(n,Name)
    end
end

Recurse(Workspace,"Banana")

The wiki says:

Instance FindFirstChild (
    string name,
    bool recursive = false
)

string name means the name of the child you want to find, this is the standard use. bool recursive = false this is the optional parameter that the tip of the day is talking about, set this to true and it will search every child for more children with the name. Example:

Here's your explorer

workspace
    Model
        Part

and an example script:

part = game.workspace:findFirstChild("Part",true)
part.Name = "Found You!"

Here's your explorer after the script runs

workspace
    Model
        Found You!