What are $f$-block elements? Give their characteristics.

(N/A) The two rows of elements at the bottom of the Periodic Table,called the Lanthanoids,$Ce$ $(Z = 58)$ $-$ $Lu$ $(Z = 71)$ and Actinoids,$Th$ $(Z = 90)$ $-$ $Lr$ $(Z = 103)$,are characterized by the outer electronic configuration $(n-2)f^{1-14}(n-1)d^{0-1}ns^{2}$.
The last electron added to each element is filled in an $f$-orbital. These two series of elements are hence called the Inner-Transition Elements ($f$-Block Elements).
They are all metals. Within each series,the properties of the elements are quite similar.
The chemistry of the early actinoids is more complicated than the corresponding lanthanoids,due to the large number of oxidation states possible for these actinoid elements.
Actinoid elements are radioactive. Many of the actinoid elements have been made only in nanogram quantities or even less by nuclear reactions and their chemistry is not fully studied.
The elements after uranium are called Transuranium Elements.