Can vs Could
Though as a couple of best known modal verbs in the English language can and could are recognized by many users it is necessary to remember that there exists a difference between can and could. These are auxiliary verbs that are used with the main verb, whose uses in grammar are often confused with. Can is in the present tense while could is in the past tense. In other words, could is the past tense of can. Therefore, basically they carry similar meanings. However, these two, can and could, are used in many ways. A small difference between can and could be pointed as can having a meaning as a noun too while could only has a use as a verb.
What does Can mean?
Can in the present tense is used to state a fact and declare ability. When used in a sentence, the word can state the fact that someone has the ability, or he knows how to do a thing and that he has the skill to do it. Can is also used to express possibility and things that can be done potentially. Can is also used to request someone to do something. Look at the following examples.
She can run fast. (Ability)
They can take the dog with them if they want. (Express possibility)
Can you call me in the afternoon? (Request)
What does Could mean?
Could is used as a past tense of can to state an ability in the past or the things one was able to do in past but not anymore. In addition to that, could express possibility as well but the time is just stated in the past. The word could is also used to state condition as is the following sentence.
If I had money, I could buy you a car.
Could is also used in making suggestions and polite requests.
Could you pass me the salt, please?
What is the difference between Can and Could?
Both can and could are used in imperative expressions usually in question form. They are used to make requests or permissions, but the use of could suggests a more polite mood. Example of this usage is this sentence following sentence.
Can I leave now? Could you get me a glass of water?
Moreover, the use of could suggests a level of doubt and uncertainty. This means that when the word could is used in a sentence the meaning may suggest that the information being expressed is maybe true or not. Can may express that a person is able to do, while could about 50% possibility that it will be done.
Can and could sometimes are very confusing, however, given the pointers above, you can get passed the confusion because simply you can.
Can vs Could
• Can is used to state a fact, ability, potential, and possibility.
• Could is used to state a past ability, condition, and possibility.
• Can and could are used to ask for permissions, make requests or commands.
• Could suggests a polite manner when making a request and it suggests a level of doubt or certainty.