Explicit memory (also called "declarative memory") is one of the two major subdivisions of long-term memory. (The other is implicit memory.) Explicit memory requires conscious thought—such as recalling who came to dinner last night or naming animals that live in the rainforest. It's what most people have in mind when they think of "memory," and whether theirs is good or bad. Explicit memory is often associative; your brain links memories together. For example, when you think of a word or occasion, such as an automobile, your memory can bring up a whole host of associated memories—from carburetors to your commute to a family road trip to a thousand other things.
Episodic memory is one type of explicit memory. Episodic memory is autobiographical: it provides us with a crucial record of our personal experiences. It is our episodic memory that allows us to remember the trip we took to Vegas, what we had for dinner last night, who told us that our friend Maryann was pregnant. Any past event in which we played a part, and which we remember as an "episode" (a scene of events) is episodic. How well we record an episodic memory depends on several factors. For example, things that occur to us in emotionally charged conditions are often stronger memories. Most people remember where they were when they heard about the World Trade Center on 9/11, or the details of a wedding of a loved one, because those were highly emotional moments for them. Another important factor is the strength with which your brain records the memory when you first experience it. If you focus carefully, and your brain is able to process what you see, hear, smell, taste, and feel very quickly and accurately, the memory is recorded with more power, making it easier to recall later. This form of memory appears to be centered in the brain's hippocampus—with considerable help from the cerebral cortex. Read more about this type of autobiographical memory and take a test to see if your episodic memories center in the same time of life as the average person's.
Another type of explicit memory is semantic memory. It accounts for our "textbook learning" or general knowledge about the world. It's what enables us to say, without knowing exactly when and where we learned, that a zebra is a striped animal, or that Paris is the major city in France. Scientists aren't sure where semantic memory happens in the brain; some say in the hippocampus and related areas, while others think it's widely spread throughout the brain. As with episodic memory, semantic memory ranges from strong (recall) to weak (familiarity). Unlike episodic memory, semantic memory is better sustained over time. We are often able to retain a highly functioning semantic memory into our 60's–after which it undergoes a slow decline.
BrainHQ for Better Memory
If you would like to improve your memory, try BrainHQ. A large study conducted by scientists at the Mayo Clinic and the University of Southern California showed that using BrainHQ exercises improved memory by an average of 10+ years. It does this by improving how the brain processes information that comes in through our eyes and ears. When the brain can record what we hear and see quickly and accurately, we form clearer memories that are easier to recall later.