Yes, semantic memory is a type of long-term memory. It falls under the “declarative” branch of long-term memory, which covers information you can consciously recall and put into words. Semantic memory specifically stores general knowledge and facts about the world, like knowing that bicycles have two wheels or that Paris is the capital of France.
Where Semantic Memory Fits
Long-term memory splits into two major categories: declarative (explicit) and nondeclarative (implicit). Declarative memory holds information you can deliberately recall and describe. Nondeclarative memory covers things like habits, motor skills, and conditioned reflexes, which operate largely outside conscious awareness.
Declarative memory then divides again into two subtypes. Episodic memory records personal experiences tied to a specific time and place, like remembering being chased by a dog during yesterday’s bike ride. Semantic memory stores facts and concepts stripped of any personal context, like knowing that dogs are mammals. The psychologist Endel Tulving proposed this distinction in 1972, describing semantic memory as a “mental thesaurus” that provides the knowledge necessary for using language and understanding the world.
The key difference between the two comes down to the type of awareness involved. Episodic memory requires you to mentally travel back to a specific moment. Semantic memory does not. You know that water boils at 100°C without needing to remember the exact lesson where you learned it.
How Facts Become Long-Term Memories
New information doesn’t land directly in long-term storage. It first passes through a region deep in the brain called the hippocampus, which acts as a fast-learning temporary holding area. From there, a process called consolidation gradually transfers the information to the outer layer of the brain, the neocortex, where semantic memories are stored more permanently.
During consolidation, the hippocampus essentially trains the neocortex by replaying information and strengthening connections between the cortical regions that were active when you first learned it. Over time, the memory becomes independent of the hippocampus entirely. This transition involves a natural loss of contextual detail. The time, place, and personal circumstances of learning fade away, leaving behind the pure fact or concept. That shift from a contextual experience to a stripped-down piece of knowledge is essentially the transition from episodic to semantic memory.
Research on human memory suggests the hippocampus may need to support new factual information for a few years after learning. After that window, the neocortex can retrieve the knowledge on its own without hippocampal involvement.
How Semantic Memories Are Stored and Retrieved
Once consolidated, semantic memories appear to reside in the neocortex, specifically in its outermost layer. Researchers have proposed that this layer acts as a convergence zone, receiving inputs from memory-related structures throughout the brain, including the hippocampus, the amygdala (involved in emotion), and areas associated with habits and routines. These inputs work together to shape and gate the storage of long-term knowledge.
Retrieval works through a process sometimes called “simulation.” Over the course of many experiences with similar things, your brain builds an idealized representation of a category. When you think of the concept “bird,” for example, your brain reactivates a generalized sensory pattern built from all the birds you’ve ever encountered. Not every piece of knowledge linked to “bird” comes up at once, though. Your brain selects what’s relevant to the current task or conversation, which is why you might think of “wings” when discussing flight but “eggs” when discussing breakfast.
There is no known limit to how much information long-term memory can hold, and semantic memories can persist for decades or even a lifetime.
What Happens When Semantic Memory Breaks Down
A condition called semantic dementia offers a striking illustration of how semantic memory works as its own system within long-term memory. People with this condition gradually lose their stored knowledge about the world while their ability to remember recent personal events stays relatively intact, at least early on. It’s the opposite pattern from what most people associate with memory loss.
The effects can be dramatic and specific. In documented cases, patients lost the ability to define common words, forgot what everyday objects were for, or developed bizarre beliefs about familiar things, like thinking zebras live in French prairies or that salads and carrots grow in forests. One patient would eat an orange without peeling it because he had lost the knowledge of how oranges work. Others couldn’t name animals, provide definitions for common words, or answer basic factual questions. When one patient was asked “What is the capital of France?” he responded, “What does capital mean?”
These cases confirm that semantic memory operates as a distinct system. You can lose your knowledge of what a watermelon is while still remembering what you had for lunch yesterday. The reverse also happens: people with hippocampal damage from conditions like Alzheimer’s disease often lose the ability to form new episodic memories while retaining much of their general knowledge for longer.
Semantic vs. Episodic Memory in Everyday Life
In practice, these two types of declarative memory work together constantly. Knowing that Rome is in Italy is semantic memory. Remembering your trip to Rome last summer is episodic memory. Over time, the specific details of that trip will fade, but any new facts you picked up (Italian coffee is served in small cups, the Colosseum is larger than you expected) may stick around as semantic knowledge long after the episodic details are gone.
This is why older adults often retain a rich store of general knowledge and vocabulary even as their memory for recent events declines. The semantic system, once established in the neocortex, is remarkably durable. It’s the long-term memory system most responsible for the accumulated knowledge that shapes how you understand and navigate the world every day.