What is Website Data on iPhone and should I delete it?

Specifically, it's very hard to tell you exactly what this data is because each site has some control over what data (if any) they store on your system, and usually that data is usually encrypted in some manner.

However, it is common for web sites to store data in cookies, and these are often used for authentication data (so when you return to a site they know who you are without you having to log in again).

Many web sites also use 'local data' storage to improve performance, by downloading content it can use locally without having to wait for the network. This is especially common with 'cloud-enabled' apps such as Google Docs where a document may be edited on your machine and synched back to the cloud.

The amount of data has no relationship to how often you use a site - you could use a site daily that stores zero data; you could visit a site once that stores megabytes - it's really up to the site author to decide how much is worth based on the user experience. Chances are you can feely delete the data - worst case is you'll need to re-log into those specific sites, maybe reset your preferences, and have to re-download any content that was deleted.

If it bothers you, delete the content. Many sites nowadays (thanks to EU regulations) post notices about their use of cookies, and you can decline/disable cookies on those sites if you're bothered. Overall, though, this storage is used to improve the user experience, and for most people the amount of space used isn't that great. You'll need to balance your own risk/rewards to decide what to do.

> If a site appears in this list of WEBSITE DATA does not it mean I already visited before? If the answer is no why have too much data sometimes?

Yes, and no... :)

In order for a site to appear, you have to have connected to that site at some point - the web browser isn't going to save data for a site it's never connected to - there are billions of web sites out there and there's no way the browser would save data for a site you've never been to.

However, thanks to the way many sites are built now, the hostname in the URL doesn't tell the whole story.

For example, you might visit www.example.com. that site might use Facebook authentication, so in the background the web page will tell your browser to connect to Facebook to try to verify your identity. Now you get a Facebook cookie, even though you never directly visited Facebook.com.

Also, the site loads ads from superadserver.com, so now you get a cookie from that site.

The site uses Google analytics to measure their site performance for search result placement, so the web page loads content from google, and now you get a google cookie.

The site might use a content delivery network to improve performance of static content such as images, so now you get a cookie from the CDN server.

The site might also use Amazon's S3 service for serving images. Now you get an Amazon cookie.

And so on...

In short, the sites you see in that list HAVE been visited by your browser. You might just not have noticed.

You may well be surprised how many domains and sites are used on a typical web page nowadays.

> And the storage data: bytes etc doesn’t mean I spend so much time in that site?

As I said before, the amount of time you spend on the site, or the number of visits, has no bearing on how much data is stored.

One site might store a 20kb cookie - and that's all it stores, even if you visit the site 20 times a day, or have it open 24/7.

Another site might store 200kb of data the first (and only) time you visit.

Another site might fluctuate depending on what you're doing... 5kb now, 1MB later on, then back to 10kb

There really is no way of predicting how much data any given site will use.

A cookie is a term kinda like a bookmark (do not confuse it with the bookmarks that browsers use). So say you are visiting a site with 10 links on the page and you explore 3 of them. Each of those links change color after you visit that link. A ‘cookie’ tells your browser ‘yeah, they’ve seen that one’. When you have your facebook set to ‘most popular’ the cookie can help the browser remember what posts you liked.

A cache is a locally stored copy of the webpage. Each webpage takes time to download. How much time depends on how large in file size the stuff on that site is and how fast your connection is. So if a local copy is stored in the cache - like a temporary folder - then it doesn’t have to redownload and you can navigate the page quicker. So if you view a video on Facebook, view it a second time and it will come up quicker because it may still be in the cache.

think of a cache asa books on your bedside table instead of books on the shelf. You like to read a couple of books to the kids each night, so you keep those out and handy. Those are in the cache, kept handy, not in the bookshelf where you’d have to go and get them.

If you see links or sites you do not recognize they could be ads that were on a webpage you viewed. Chances are patientpop and pbwstatic in your screen cap are ads that were on a page you visited.

You go to facebook. All that stuff on the far right? All those ads? They will have the site name of the company that dishes them up. So a single visit to facebook can give you a dozen or more of those listings.

Then the facebook you see on that screen cap is probably websites that have the facebook icon on them - such as ‘this is our facebook page’.

Website data is a generic term for data that comes from a website. it can consist of cookies - little things that tell the browser that you’ve been there, and cache is local storage but can also be categorized as website data.

> I don’t have facebook. I’m not using facebook.

Many sites use Facebook for integrated registration (e.g. you can log into them using your Facebook account).

Even if you don't have a Facebook account, the sites don't know that, so they reach out to Facebook to ask, and the result gets stored on your system.

> Cookie, cache and website data are the same?

yes... and no :)

They are the same in that they are data related to the site in question, but they have different purposes:

Cookies are snippets of data requested by the site to be stored on your system (e.g. authentication ID)

Cache is data that the browser has determined should be cached (saved locally) to improve performance - typically images and stylesheets that subsequent views to the site can re-use without having to download again). Sites don't usually control this, although they can influence it by adding tags to each image to indicate if it could/should be cached, and for how long.

Web Site Data is other data that the page itself has asked to save on your system. As I mentioned before this could be documents that you edit or other data that the page generates. on your machine that isn't (yet) uploaded back to the server. The specifics of this are 100% dependent on the site in question.

It can be cookies, cached images and data. Possibly login data etc.