Here, ul has 8 children(8-li) on total.
And, each li has 7 more siblings(i.e brothers/sisters). Now, suppose you want to identify the 1th li and also 2nd li where only third li can be identified uniquely.
Identifying the 3nd li element, via the xpath
//li[@class='dropdown forum_blog hidden-xs']
NOW,
if we want the identify the 1th li then how do we proceed???
Here we can make use of the preceding-sibling to
identify the 1st element by
//li[@class='dropdown forum_blog hidden-xs']/preceding-sibling::li[2]
Where as the 2nd element can be identified as
//li[@class='dropdown forum_blog hidden-xs']/preceding-sibling::li[1]
Note: preceding-sibling::[1] and preceding-sibling::[2] work in descending order.