There are a few methods available to add captions to images that appear in your Joomla articles. The easiest solution is to use a free extension called EasyImageCaption.
1. Download the extension and install it as normal. Review lesson 12 - Extensions - of the Build a Joomla Website training if necessary.
2. In Administrator, go to Extensions - Plugin Manager. Find the newly installed extension (labeled EasyImageCaption) and click it to enter Edit mode.
3. Set Enabled to Yes.
4. Review the various options in the right column. The default settings are all you need, but it is helpful to have an understanding of the options available. The main one to consider is "Use this tag" which is initially set to "ALT". For the sake of keeping this tutorial simple, I will leave this as is, but if you are an advanced user, see the comments at the bottom of this article. Remember to click Save when you have finished.
5. Go to an article and insert or edit an image as normal. When you click the image button, a new window opens with various options. If you are using the standard editor that comes with Joomla, you will see an option labeled Image description. Enter your caption into this box and save the article. The caption will not appear in the editor, but it will be there on the front-end of your site. If you are using a different editor, such as JCE, the option will be labeled Alternate Text or simply ALT.
1. In step 4 above, I suggested to leave "Use this tag" set to ALT but I prefer to use TITLE. The problem using ALT means every photo will have a caption and there may be occasions where you simply don't want one. Sure you can just leave out the ALT tag but it is considered best practice to always include some ALT text for accessibility reasons. Also you might not want to use the same text in your ALT description as you do for the caption. However you can stick with using ALT and exclude certain sections, categories and articles by entering the appropriate IDs at the top of the plugin parameters.
2. You can apply basic formatting to the captions. This is explained in the left column of the plugin page. However to activate this facility, you need to look in the right column and click Caption Styling (under Plugin Parameters). Set Internal Styling to On. Save and enjoy.