How do credit cards work?

[DWarrior]

I'm thinking of getting a credit card, but I don't understand how the Grace Period works.

Say the terms are 25 days grace period if there is no previous balance or balance is paid in full.

Assuming I paid my June balance in full, and I buy something on July 2nd, does that mean I don't get charged interest until the 29th? If I pay my July balance as usual, say on August 5, does that mean I get charged interest on the July 2 purchase from July 29th until August 5? So does that mean I should be paying my CC bill a couple of times a month if I want to avoid interest?


Another question is say I have a June balance of $100. I make a minimum payment of $20, so I still have a remaining balance of $80. I then make a July 2 purchase of $10, with no grace period. I then pay off $80, effectively paying off my June balance. If I then make a purchse on July 10, does that purchase get the grace period, since I technically didn't have a previous month's balance, or do I get hit with no grace period?