To, Too, Two, There, Their, They're

I am not the best person when it comes to grammar and I know I’m not.  But there is one thing I CANNOT stand and seems to make me mad every time I see it.  I absolutely HATE when people use the wrong to or there.  Like some people always feel the need to type too.  I don’t understand why you need to add an extra o that doesn’t need to be there.  There are only certain times one should put that extra o, you don’t need to type it all the time.  Another person I know always put their.  Their shows possession.  Not everything you type has an owner.  I just don’t seem to get it!  I never understood what was so difficult and confusing about the different uses of these words.  We have been learning the rules to these words since elementary school and I just don’t realize why some people refuse to get the hang of it.  If I’m reading a text or tweet or something of that sort and a person uses either of these words wrong I just stop reading and keep it moving.  Everybody has their pet peeves, and this just happens to be one of my biggest ones.