Too v. So

The use of too and so is a common mistake among English speakers and writers. So when is it correct to use too and so?

I get confused, too. That's why I consulted two dictionaries: Dictionary.com and Merriam-Webster.com.

Too
–adverb
1. in addition; also; furthermore; moreover
Example: We have to sell the house and car, too.

2. to an excessive extent or degree; beyond what is desirable, fitting, or right: too sick to travel.
Example: This condo unit is too large a house for you, don't you think?

3. more, as specified, than should be
Example: Don't get too near the fire.

4. (used as an affirmative to contradict a negative statement)
Example: I am too!

5. extremely; very
Example: She wasn't too pleased with his behavior.


So
1 a: in a manner or way indicated or suggested.
Example: Do you really think so.
—often used as a substitute for a preceding clause
Examples: Are you ready? I think so.
I didn't like it and I told her so.
b: in the same manner or way : also
Example: I worked hard and so did she
c: thus 1
Example: For so the Lord said — Isa 18:4(Authorized Version)
d: then, subsequently
Example: After this long meeting, I'll have dinner and so home and to bed.

2 a: to an indicated or suggested extent or degree
Example: I had never been so happy.
b: to a great extent or degree : very, extremely
Example: He loves her so.
c: to a definite but unspecified extent or degree
Example: I can only do so much in a day.
d: most certainly : indeed
Example: You did so do it.
e: most decidedly: surely
Example: I so don't believe you.

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