Jet, grammar and punctuation are two distinctly different things.
A period ( one of these funny little marks . ), is a punctuation mark. It is just one of many little marks we can use, and make what we write easier to follow and understand.
Grammar on the other hand is how we put the correct words together to make an intelligent sentence and / or paragraph.
Here is an example of poor punctuation and grammar:
"Hey MaddogWX you are saying that i got bad grammer. You didnt even put a period at the end of the senteces. One suggestion check yourself before you reck yourself."
Here is how that statement might look if I employ a bit of grammar and proper punctuation:
"MaddogWX you say that I have bad grammar, yet you did not put a period at the end of your sentence. I suggest that you check yourself, before you wreck yourself."
You may have the quotation marks, the comma's and the periods in the example above, as I am quite finished with them.
Hopefully you will get many opportunities to use them in the future.
My gift to you;)
RTR