Drupal 7 keeps asking for FTP login when trying to install modules/themes using the web interface

After changing ownership of a Drupal installation to the SFTP user using the folder, Drupal started to show peculiar behaviour. Whenever I tried to install any module or theme through the web interface, Drupal 7 would ask for the FTP login credentials. Although making changes through SFTP is okay, sometimes the web interface is much more convenient.

Problem: Drupal 7 would not allow installation through the web interface without needing the user to type in the FTP login.

Impact: Inconvenience.

Creating a "NEW!" flag in Drupal 7 using entities and Display Suite

Have you ever wondered how to flag new content in Drupal? In a website I've worked on, I wanted to find a way to create a "NEW!" flag to flag new content. (Note: If you were only wanting to create a flag that says "NEW!" on the node page for the piece of content you can just use a view, but what if you wanted to have something that marks content as new in a list of node teasers?) Here's how I did it in Drupal 7 using a custom code field with Display Suite.

Problem: A flag or field was needed to display "NEW!" for new content.

Impact: Users won't be able to pinpoint at a glance the new content.

Errors viewing website after changing Drupal theme

While I was pretty new to Drupal, I started playing around with themes, but after changing the theme I started seeing error messages at the top of each webpage. The answer was simple: I forgot to clear the caches!

Problem: Error messages after changing the theme in Drupal.

Solution:
This one's a short one. In Drupal 7, go to Configuration > Development > Performance. You'll see a button labelled "Clear all caches". Click that and you're done!