The whole purpose of having categories and tags in WordPress is to ensure that your content is easier to find. If you have a site and are looking to make sales, common sense dictates that you make it as easy as possible for customers to find what they are looking for. As a means of comparison, categories are like the dishes you see on a restaurant's menu where tags are like the elements which combine the dishes on the menu.
If your blog is all about the world of cameras, you need to make it easier to navigate. There are hundreds of different camera types so it is essential to break them up into categories for easier public consumption. For example, there are point and shoot cameras, digital cameras. SLR cameras etc. In order to divide cameras up into these sections, go to the Categories part of your WordPress blog and select whatever categories you wish. In the event that you do not have any suitable categories, simply click on the 'New Categories' tab and come up with a new one.
If you are actually discussing a particular kind of camera, you could assign what is known as a 'parent category'. In this instance, a 'parent category' would be a type of camera such as an SLR camera. Add this 'parent category' and you will find that it appears underneath your original camera category. Tick the box and it will be applied to the post.
When it comes to dealing with tags, you need to remember that these are far more precise than categories and are used to relate to a particular post. You are allowed to add as many tags as you wish with the whole idea being to add keywords in order to accurately describe the contents of what you have just posted. When you are adding a tag, place a comma after each one. You can also click 'the most popular tags' option and you will find a list of previously used tags that can be quickly incorporated into your new post.
An example of tags in action would be if you were writing about a Nikon D60 SLR digital camera, you would add tags such as 'Nikon', 'D60', 'SLR', 'digital camera'. In fact, that is exactly what your tag box should look like, separate words divided by a comma. Simply click 'add' and the tags are added.
If you have completed the above steps correctly, visitors to your blog will be able to quickly see what you have written divided into categories. This is particularly useful if you enjoy writing about a variety of topics. For example, you may have 'cameras', 'cars' and 'football' on the right hand side of your page. Visitors can click on what they are most interested in. Thanks to the tags you have added, visitors can also see sub-categories which should enable rapid navigation. This makes your site far more attractive to web browsers. There is also a specific 'Tag Surfer' option which is available to WordPress users. This speeds up the process of finding interesting content.