Recognition vs Recall
It is easier for an individual to recoganize something with which they have had previous experience than to have to completely recall something from memory.
Individuals are normally able to get more correct answers on a multiple-choice test than a test that requires them to write-in a correct answer because they only have to recognize the answer.
To write-in a correct answer forces the individual to completely recall the correct answer.
It is easier to read a foreign lanuage than to speak it. Speaking requires recalling the actual words that you want to say and the grammar rules for that language.
When introducing information to your user you can use memory aids that rely on recognition.
For example the computer keyboard allows a user to save a file by using a combination of two keys one of which is S which is the first letter of SAVE.
Which make it much easier for use to remember.
PC alt + S
Mac command + S
When the user is required to complete a task on your site give them visual clues and hints so that they can recall information as the move through the task.