When can we use the Instance:IsA in roblox studio?

When can we use the Instance:IsA in roblox studio it mainly says that we can use it to check class name but I see people use it on diffrent things is it true that we can use it for many things like on a if statement or things.

if game.Workspace.Part:IsA("Part") then
print("Part Exist!")
end

You can use Instance:isA when an instance has special functions. I also recommend using BasePart instead of part. Example:

local part = pathhere or script.Parent
if part:IsA("TextButton") then
	part.Text = "eueueueueue"
end

So yeah, IsA() is simply to check if it's a specific Instance.

Examples like this is to check if something is a script and you don't want to include it in a table full of parts. Also it can help find out if it fits the requirement of a function

function TestForPart(Instance)
	if Instance:IsA("BasePart") then --basepart includes any type of part
		return "Is A Part"
	else
		return "Not a Part"
	end
end

print(TestForPart(workspace.Baseplate))