1. Introduction
In this tutorial, we’ll review the differences between deprecated, depreciated, and obsolete. Firstly, we’ll define the terms and describe them. Then, we’ll review the differences between them.
Software development usually involves the release of different versions of software. With each of these versions comes different functionalities. With time, some functionality is updated, others are removed and some are added. The concepts we’re to discuss in this article revolve around this.
2. Deprecated
The term deprecated refers to a functionality that still exists in software whose use is not recommended. A functionality that is deprecated is likely to be removed in the future hence it is not advisable to use it. Deprecated functionalities are usually replaced or updated with newer versions.
For example, assume we have some software 
, that has a function 
that executes the addition operation on two variables of different types except long floating-point numbers. The developers release version 2 of software with a new function 
which executes the addition operation on two variables including long floating-point numbers.
Now, in this case, the function can still be used for all variables but will not work on long floating-point numbers. We refer to the function as deprecated.
In most cases, the use of deprecated features or functions raises warnings or alerts to inform the user that the function is deprecated and will be removed in the future:
3. Depreciated
Depreciation is a term used to refer to the decrease in the value of an item or thing, such as a car. In programming, it is often used mistakenly to refer to deprecated.
4. Obsolete
Software functionality that is obsolete refers to a feature or functionality that is no longer supported by its developers. In some cases, it is no longer in use. In contrast to deprecated features, obsolete functionalities are deemed unusable or irrelevant. Hence they are not supported at all.
For example, assume we have some software 
, that has a function which adds two variables of different types except long floating-point numbers. However, the function consumes so much space in memory. A new method of computation is discovered; hence the developers release version 2 of software .
Version 2 comes with a new function 
which performs the addition operation on two variables while saving space in memory. Now, in this case, the function will be removed and replaced by the function . The function is now considered obsolete as it longer serves any purpose.
The use of obsolete functionalities or features is strongly discouraged as it may raise errors or generate erroneous output. Due to this reason, calling an obsolete feature will usually generate an error message:
5. Key Differences
The key difference between deprecated and obsolete is that deprecated features are supported while obsolete features are removed or replaced in current versions of the program or software. Additionally, the use of deprecated features will generate a warning message. However, the program will still run.
On the other hand, using obsolete features will cause errors in the program and generate error messages as well.
6. Conclusions
In this article, we’ve discussed the difference between deprecated, depreciated, and obsolete. Firstly, depreciated is mistakenly used to refer to deprecated. Deprecated means a function can be used but is not encouraged, while obsolete means a function should not be used as it is no longer supported.