What are memories? how does it work?

Memory is the mental capacity or faculty of retaining and reviving facts, events, impressions, etc., or of recalling or recognizing previous experiences.

How does it work:
The synapses appear as bright spots along dendrites (the branches of a neuron that transmit electrochemical signals). As the brain processes new information, those bright spots change, visually indicating how synaptic structures in the brain have been altered by the new data.

There are three majior process involved in memory: encoding ,storage, and retrieval. In order to retrieve new memories info must be changed into a usable source known as encoding once info is sucessfully encoded it is stored in the memory.