Saul's example's are correct, but I'm afraid that the difference isn't about past and future. 'Since' is about a time period which began at a point in the past and is still continuing. This is why it is used with the perfect tenses. However, 'until' is not only for the future. You can use it with any tense. For example, you would say - Our meeting yesterday lasted until 10pm. - which is clearly about past time. Try thinking about it this way: 'Since' tells you when a time period started (from....) 'Until' tells you when a time period finished/finishes/will finish (to...) '

We use "since" to say when something started, but hasn't finished. We use "until" to say when something has already finished, or will finish. Examples: I have been learning Chinese since 2013. I haven't seen my family since June. I have known my best friend since high school. It has rained 3 times since last night. The rain won't stop until tomorrow. I will study Chinese until I am fluent. I went to school until I was 18. I watched TV until 11pm last night. http://www.englishgrammar.org/using-since/ http://www.englishgrammar.org/until-and-till/ Hope this helps!

'From' describes when an action starts. 'Until' describes when an action ends. 'Since' is similar to 'from', but you can only use it if the action is happening at the time of speaking. Ex. "I ran from 5:00 until 7:00." "I will run from 5:00 until 7:00." In these examples, 'from' and 'until' give a time frame in which I ran. "I have been running since 5:00." This means that you started running at 5:00 and you're still running at the time of speaking. This logically requires a present continuous tense. You can't use 'since' with other tenses.

Until -> future (action starts in future time) Since -> past (action starts in past time) Examples: 1. I have been correcting some tests since 10:00 am today. 2. I will be correcting some tests until 10:00 am tomorrow.

So, can we use SINCE to refer to a point of time in the past? Can we use UNTIL to refer to a point in the future? Is that the general consensus? That is how I see it.