We hold on to different kinds of memories.
<ul>
<li>Short-term memories last seconds to hours and long-term memories last for years.</li>
<li>We also have a working memory, which allows us to keep something in mind for a limited time by repeating it.</li>
<li>Declarative memories are memories you experience consciously, like facts or "common knowledge."</li>
<li>Nondeclaritive memory unconsciously builds up. These include procedural memories, such as riding a bicycle or playing the piano.</li>
</ul>

The different kinds of memories

For a short-term memory to become a long-term memory, it must be strengthened for long-term storage. The process is called memory consolidation and occurs using several processes.
Long-term potentiation consists of individual nerves changing themselves to grow and talk to their neighboring nerves differently. The remodeling modifies the nerve's connections, which makes the memory stable.

Memory consolidation

Memories are held within groups of neurons called cell assemblies. They fire as a group in response to a specific stimulus, such as recognising your friend's face. 
The more neurons fire together, the more the interconnection of the cells strengthen. We experience the nerves' collective activity as a memory.

How we experience memories

When we recall a memory, many parts of the brain share information, including regions that do high-level information processing, regions that deal with our senses' new inputs, and the region that help coordinate the process, the medial temporal lobe.

Recalling a memory

By studying people with amnesia, it seems that short-term and long-term memories don't form in precisely the same way, nor do declarative and procedural memories. 
<ul>
<li>Emotional responses such as fear occur in a brain region called the amygdala.</li>
<li>Memories of learned skills are associated with the region called the striatum.</li>
<li>The hippocampus is essential for forming, retaining, and recalling declarative memories.</li>
<li>The temporal lobes play a critical role in forming and recalling memories.</li>
</ul>

Where your brain keeps memories

Human memory happens in many parts of the brain at once, and some types of memories stick around longer than others.

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