Is there any difference between 'ever since' and 'since' when used in a sentence? Are they same and interchangeable to use? Please explain with examples.
The preposition since is used to refer back to a previous point in time:
It’s been years since I rode a bike.
Since joining the company, I've been promoted twice.
Since also has meanings with no reference to time:
Since you ask, I'll say yes.
Since he didn't study, he didn't pass the exam.
Ever since is used when you want to emphasize that something has been true from "from that time to this".The "ever" can suggest a continous thing and suggest against the possibily that something has happened only intermittently since:
Ever since we met, we have been been good friends.
His grandmother doesn’t go for walks on her own ever since she fell at the bus stop.
My father has not smiled ever since my mother died.
To see the difference, here are two more examlpes:
My back has been aching since I fell off the ladder.
Ever since I fell off the ladder, my back aches.
To make a long story short,"ever" is just an intensifier. There's no principal difference in meaning when you add it or remove it.
The word since is a subordinating conjunction if it introduces a clause as in:
You must serve detention after school today since you were tardy. Since you were tardy, you must serve detention after school today.
Notice that in the second example sentence there is a comma after the subordinate clause.