Why is there a beyond-limit charge in credit cards if there is a credit limit?

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I received my credit card's bill last week. I haven't tried going beyond the limit though but what caught my attention that day was the note that came with my bill. The note contained a list of fees/penalties and one of them was beyond-limit penalties. I cannot seem to understand why there is a beyond-limit charge when there is a credit limit. Does it mean that they are not too strict with credit limits?...and that we can actually spend beyond credit limit especially when we are not aware that we are beyond the limit provided that they charge us with the penalty? Why not suspend the credit card in the meantime?