Try and error / Trial and error, or trial by error, is a general method of problem solving, fixing things, or for obtaining knowledge "Learning doesn't happen from failure itself but rather from analyzing the failure, making a change, and then trying again." This approach is more successful with simple problems and in games, and is often resorted to when no apparent rule applies. This does not mean that the approach need be careless, for an individual can be methodical in manipulating the variables in an attempt to sort through possibilities that may result in success. Nevertheless, this method is often used by people who have little knowledge in the problem area. http://en.wikipedia.org/wiki/Trial_and_error

It's a way of doing something when you're not completely sure, at random. For example, in many action movies characters use try and error tactics when defusing a bomb (but, you know, eventually their tries aren't always successful).

It is trial and error= if at first you don't succeed, try again until you do

yes

Could be trial and error tactics. A tactic of searching for good method. You have 3 ways. Try 1st - error (bad method choise), try 2nd error, try 3rd -success. To your last question, you are right.