# Why d block elements are called outer transition and f block elements are called inner transition???? Please explain. Thanks a lot

Well, if you insert the $f$ block elements in their proper place, you would have an extended periodic table:
And so, the $f$ block elements are "inner" transition elements, being between the $\text{Sc}$ group and the rest of the $d$ block. The $d$ block is then "outer", as they are on either side of the "inner" transition metals.
The $f$ block elements have rather unusual electron configurations, and you probably won't need to know them in your lifetime. Should you ever want to just for fun, I've written a detailed explanation of why there are so many exceptions to their electron configurations.