What is a Internet Cookie?

If you logged into this site, you probably have a Wordpress authentication cookie in your web browser.  Unless you recently cleared it, your browser probably has dozens or even hundreds of these small pieces of code.  But what are they, and what are they used for?

Internet cookies are small pieces of code that are downloaded to your internet browser.  Usually, you get them from websites that you visit.  These cookies have many different functions.  Some of these functions improve the user experience, while others are potential problems.  For example, a very common type of cookie is an “authentication cookie”.  This is used to store login information.  Basically, this is one of several possible ways a website knows who is logged in.  While many modern websites do not use this method, in early commercial websites cookies were often used to keep track of what a user had in a shopping cart.

However, while most cookies are safe cookies may cause problems on your computer.  Cookies can be used to track things you do online.  They do not necessarily stop sending information when you finish using a site.  This can be a serious privacy issue.  For example, a website you visited months ago may still be receiving information from your computer.  This can be a risk to privacy and may open you up to security threats.

You may choose to block cookies from your browser settings.  Most internet browsers have an option that will allow you to block cookies.  Another option, and one I recommend, is to clear your cookies occasionally.  Many computer optimization software tools clear Internet cookies.

I hope this answers some questions and I hope you enjoyed reading this.

Please send me more questions in the comments section!

What is a Vector Graphic?

Two terms you will encounter frequently when you discuss creating images on a computer are “vector” and “bitmap”.  Both are types of image and both have distinct uses.  You have probably encounter both types many times without noticing.  The primary difference between the two types is how the information is stored.  This difference leads to several important distinctions in how the images appear and how they are used.

In a bitmap image, which is sometimes called a raster image, the picture is in the form of pixels.  Each pixel is in a specific location and is a very specific color.  For example, a digital photograph consists of thousands of tiny squares which create images.

For example, just look at this photograph of some purple flowers.  It consists of approximately, 800,000 pixels and when you zoom in on it tightly you can see them.

Just look at this very tight close up on one of the flowers.  You can see around the edges of the flower where the pixels are visible.

All bitmaps store information in the form of pixels.  This has the advantage of being able to support very detailed images, that have realistic color variation.  However, this can also be a disadvantage.  As you can see, when you zoom in tightly on a bitmap, the you see individual blocks of color.  This is why there is often a limit on how much you can enlarge a photograph before it begins to look odd.  This is also why measurements like “dpi” or “ppi” (which stand for “dots per inch” and “pixels per inch” respectively) are relevant.  The more pixels in one inch, the more you can enlarge the image before it starts to look strange.

Vectors graphics work on a completely different principle.  Rather than storing the image as individual pixels, it stores the image mathematically.   Vector images are understood in terms of points, curves and mathematical formulae.  This allows for the storage of extremely complicated shapes.  For this reason, vectors are very scalable.  To increase the size of the vector image, simply adjust it mathematically and the image will be unchanged.  Vectors are excellent at shapes and designs.  They are frequently used in logos and drawings.  However, they do not work well for subtle color variation or photo realism.  Vector images often look like drawings or have a “cartoony” look.

For example, here is a very roughly created image of a similar flower.  It consists of five round shapes, each with a few additional points to give them more “petal” like appearance.

Obviously, this is a very crude graphic, but it does a good job of illustrating some of the characteristics of vectors that might not be as obvious in a more complex drawing.  Each “petal” is defined by six nodes and each node two other points determining the curve of the line connecting it to the next node.  The center of the flower is simply an ellipse.  However, because the shapes are defined by curves, when you zoom in, there is no change in the image.  You can zoom in as tightly as you like or increase the size of the image and the curves do not change.

This is a zoomed in look at one of the petals.  Notice how it keeps its shape and color.

Both bitmaps and vectors have many uses.  I enjoy working with both.

I hope you liked reading this article and please post your questions in the comments!

Note: Most webpages, including this one, prefer to handle bitmaps rather than vectors.  All of the vector images in this post were converted into bitmaps for viewing.

File Compression Or How to Zip and Unzip Files

This is another post in my series on essentials of dealing with files.  In this post I will be talking about file compression and how to zip and unzip files.  Compressing files is very useful when sharing files over a medium that has an upload limit.

All files stored on a computer have a specific size, which is usually given in bytes.  However, there are times when you would prefer files to be smaller.  For example, many email clients will only allow you to send files of a particular size.  This is a problem if you want to send larger files.  One solution to this is by using file compression.  This packages the files and makes them smaller.  However, in order to use the files they must first be unpacked.  There are many different types of compression software and many different compressed file types.  There are some differences, but most compressed files behave very similarly.  Compressed files can be identified by their file extension.  Common file extensions include “.7z”, “.rar”, “.tar” or “.zip”.  The most commonly used type is a “.zip” extension.  In order to unpack the file you need the proper software.  A Windows computer has the capacity to compress and decompress zip files preinstalled, but to use other types you will probably need to download software.  One of my favorite file compression tools is the open source tool 7-Zip, which has the capacity to handle many different types of file compression.  You can download it for free here.

If you are simply using zip files, you can use the software that is preinstalled on Windows computers to compress and decompress your files.

If you would like, you can follow along on your computer, just pick out some files that you would like to try zipping up.  There are many different methods that you can use, but I rather like this one.  You may wish to experiment a bit to see which methods you like best.

To Zip a File:

Start by finding some files that you want to compress. For this demo, I will be using some files I just created, but you can use any files you like.

Next, select all of the files that you want to compress.  To select more than one file, just hold down the Ctrl key before clicking on the file.  Then right click while the files are selected and click “Send to” and then click “Compressed (zipped) folder”.  Depending on your version of Windows these commands may look slightly different.  This creates a new folder that is “zipped”.  You may need to rename it, as it is by default named after one of the selected files.

You may notice on the screenshot, that there is also an option to select 7-Zip.  That is my favorite downloaded compression tool and it is used in a very similar manner.

Either tool creates a single compressed file that can be transferred far more easily than the original files.

Unzipping a File

Extracting a compressed file is just as easy as compressing a file.  If you using a zip file, you can use the preloaded software on Windows, but if you are using another type you need software.

When extracting the files from a zipped folder, first select the folder.  Then, right click and select “Extract all”.

Next, you need to select a destination file.  When you extract files, you create a new folder that contains the extracted files.

After that, you can access the contents of the file as you would normally.

I hope you enjoyed this tutorial, and please post other topics for me in the comments area!

Saving and Overwriting — Or What is Difference Between Save and Save As?

This post is dedicated to a very common mistake that can cause a great deal of frustration when made.  How many of my readers are familiar with this scenario, I know that I certainly am.  You open up a document in a word processor.  The document is very long and you decide that you want to make a shorter version to print out and save the long one for an electronic version.  You delete a lot of text, some figures and a few charts.  You think you are finished and so you go to save the document.  Here is where horrible mistakes are made.  You are distracted, you click “Save”, because that is what you do with documents, and go on about your day.  When you go to get the long version out to print, it is gone and in its place is the much shorter version that you just created.  You have just been a victim of an overwritten document. If you had clicked “Save As” you would have stored your shorter version under a new name and instead of losing your original you would have had two separate documents.  This is why the distinction between “Save” and “Save as” is so important.

When you save something, you are replacing whatever currently exists at that file location with what you are currently working on.  This is fine as long as you do not want to access the old version.  When you use “Save as” you are creating a new file location distinct from the original one.  This allows you to have more than one version of the same document.

When dealing with the scenario we discussed earlier, it is sometimes possible to retrieve overwritten documents.  Some software, such as Microsoft Word, allows you to access previous versions for just this purpose.  Also, you may use backups or various software to retrieve overwritten files.

I hope this is useful and thank you for reading!