How to use 'who' and 'whom' correctly

Students of English often find it difficult to differentiate between ‘who’ and ‘whom’. Well, in this post, I will try to explain how to use both correctly.

1 ‘Who’ can be used in front a question. For example, you can say “Who sat here just now?”

2 ‘Who’ can also be used to replace the noun in front of it in a compound sentence. For example, you can join these two sentences by ‘who’:
a) John is my friend.
b) My friend often helps me in my work.
The compound sentence formed by joining these two sentences is:
John is my friend who often helps me in my work.

3 ‘Whom’ is used to replace an object in questions. The following are one statement and one question involving the use of ‘whom’.
a) Statement: I saw Albert yesterday.
b) Question: Whom did you see yesterday?

4. ‘Whom’ is also used after ‘prepositions’. The sentences below illustrate this point:
a) Leslie is the man in whom I confide.
b) Susan was the girl to whom I gave a present two days ago.
c) From whom did you receive this pamphlet?
d) George is my eldest brother with whom I share my joy and sorrow.