Analogy for Addressing Modes

Consider a register as a post-it. The AVR has 32 of such post-its. Each post-it is an 8-bit item, it can store 8 independent bits.

Memory is a little booklet. Each page (memory location) in the booklet stores 8 bit. Furthermore, each page has a page number (an address). In the case of the AVR, a booklet can be as thick as 65336 pages. The first page has a page number of 0, while the last page has a page number of 65535.

When represented in binary, 65335 is $1111 1111 1111 1111_2$. This means it takes two post-its or two pages in the booklet to store an address.