What is a caching level


A cache (German: hiding place; pronunciation: kesch) is a fast memory with a relatively small storage capacity, which is positioned between the central processing unit (CPU) and the main memory. It helps to avoid access to the hard disk or time-consuming recalculations by temporarily storing certain data and making it available more quickly if necessary. The cache stores a copy of the current request and to a certain extent reflects what is on the requested medium.

How it works [edit]

In order to enable efficient access, frequently used program parts and calculated data are stored in the cache and are therefore available more quickly. The cache acts as a buffer between the main memory and the hard disk and enables certain threads to be processed more efficiently. Data that will soon be required can also be loaded in advance from the slow background memory and made available in the cache.

The cache memory is divided into hierarchies called levels. This provides information about the position that the respective hierarchy occupies in the data stream. A level 0 cache (L0) is the title of a small memory of a few bytes that decouples the data stream in the central unit at the beginning. L1 and L2 are internal caches, whereas the level 3 cache (L3) is a separate memory on the motherboard (main board). Each cache level can query so-called hits and misses: If data from a current user query is identical to that already in the cache, it is a hit and the current process can be handled using the cache. Otherwise it is a miss and the process may need to access the hard drive.

Areas of application [edit]

In addition to the most popular memory caches, there are also caches for floppy disks, CD and DVD drives. These storage media use a different, conventional storage technology to temporarily store data. In terms of web applications, a cache is a temporary storage device that caches a website, form data or available media such as videos or images so that this data does not have to be reloaded when the resource is accessed again. Such caches are part of the software and use certain resources that the software uses anyway.

A browser's cache loads data that the user has either already entered or that the server makes available - such as forms or videos. This data is also known as temporary files because it is only temporarily stored. Cookies and user data such as passwords are also stored in the cache.[1] If the cache is to be deleted, users can find appropriate instructions on the Internet that are suitable for the respective browser.[2]

Relation to SEO [edit]

Search engines like Google also have a cache in which a kind of snapshot of the respective page is stored. This copy is stored on the search engine's own servers and can be called up again via the cache regardless of the current availability of the website. This can lead to legal problems, which the website operator should always be aware of and inform about before registering the URL.

However, Google's servers cannot afford to make websites directly and always up-to-date available. Every visit to a website from the SERPs is an image that the Google crawlers have collected at a certain point in time in order to save it in the index. What the user is presented with is a copy of the website from the index. American law covers this copy with the Fair Use Act. There is an impractical loophole in German law.[3] In any case, the authors of websites are likely to have a fairly large interest in being found via Google's search result lists - even if these are basically images of websites from the Google index.

References Edit]

  1. ↑ Empty the cache and delete cookies. support.google.com. Retrieved April 23, 2014.
  2. ↑ How can you delete temporary files (cache)?. faz.net. Retrieved April 23, 2014.
  3. ↑ Caching on search engines. dsri.de. Retrieved April 23, 2014.

Web links [edit]