Your: Belonging to you (possessive). Your coat, your socks, your ability to spell correctly.
You’re: Abbreviation for you are: You’re wearing socks, and you're spelling you’re correctly.
It’s: Abbreviation for it is. It’s hot today.
Its: Belonging to it (possessive). Look at its socks.
Their: Belonging to them (possessive). Their socks.
They’re: Abbreviation for they are. They’re wearing socks.
There: Place. Over there are the people wearing socks. Here, there and everywhere.
Affect/Effect : Affect is a verb. Effect is a noun. You Affect an Effect. RAVEN (Remember Affect Verb Effect Noun)
Till: A cash register, or to prepare the soil for crops to be sown
‘Til: Abbreviation for until.
And finally, Facebook may be the mecca of all things social media but in one facet it is grammatically incorrect.
Invite is a verb. You invite someone to be your Facebook friend.
Invitation is a noun. You send them an invitation to be your Facebook friend.