How do gpa's work?

How do people figure out there GPA? and what is their GPA in the first place? does it have everything to do wtih your grades, or just the classes you take? and for the grades, does it just count for the average of all your grades put together or it is...

each marking period? and would getting 1 C ruin a GPA? because I think I got a C on my report card and yea im depressed so I want to know.

Depends on the scale your school uses.

Schools with a 4-point scale give 4 points for A's, 3 for B's, 2 for C's, 1 for D's and 0 for F's. Some schools assign fractional points for pluses or minuses. Sometimes A- or B+ are 3.5 and sometimes A- is 3.7 and B+ is 3.3 depending on the school. My college didn't consider pluses or minuses in calculating our GPAs, B- B and B+ were all worth 3 points. Your GPA is the average of the number of points for all classes attempted..

A weakness of this system is that it gives the same credit for all classes. It might be easier to get an A in basket weaving than it is for Advanced Placement Calculus. I remember my High School guidence councelor advising students to only take harder college prep classes if we were sure we could ace them since an A in the regular class will be better for our GPA than a B in the harder college prep class. Some schools use a weighted GPA where AP or honors classes get an extra point or two. In weighted GPAs an A in a harder class may be worth 5 or 6 points instead of 4. This encourages students to attempt harder classes even if they are not sure they can ace them.

Since a GPA can refer to a single semester or be cumulative sometimes CGPA is used to indicate your GPA for your entire program vs. a specific term.

This is how most US GPAs are calculated. Schools in other countries use different systems.

Generally GPAs are expressed with 3 significant digits so a single C will probably lower your cumlative GPA a few ticks and of course it would lower your short term GPA more .