的（てき） is a 接語尾（せつごび） (suffix) in Japanese that has two primary uses. The first use is very similar to ‘as’ or ‘for’ in English, and means ‘considering/within the category of (A), (B)’. The second use primarily relates to people, and will be covered later. As a single word, 的（てき） is often likened to adjective endings such as ‘~ly’, ‘~like’, and ‘~al’.
To use 的（てき）, attach it to the end of a noun that you want to express as being the focus point of either a verb or a noun that will come later in the sentence. When describing a noun, 的（てき） will be followed by な (meaning that it becomes a な-Adjective
). When describing a verb, it will be followed by に (making it an adverb).
You don't have to get that emotional. (Speaking in terms of emotions, there’s no need to get like that)
Please clean the filter regularly. (Speaking in terms of regularity, please clean the filter as such)
That is a personal way of thinking, isn't it? (Speaking in terms of individuality, it’s that kind of thought, right?)
Earlier, some religious people came to the house. (Speaking in terms of religion, some people like that came earlier)
The second common use of 的（てき） is specifically with the names of people, and highlights that (B) is something that is being considered in regard to (A). (A) being the person mentioned. This may be used either positively or negatively. In English, this is similar to ‘that’s so (A)’, or ‘just what you’d expect of (A)'.
In a Lisa-way, what do you think? (What is your opinion)
That is such a Tanaka-way of thinking.
The easiest way to understand and use 的（てき） correctly almost all the time, is by knowing another common suffix, 圏（けん）. Let’s look at how these suffixes compare:
圏（けん） - Occurring in the sphere of (A), (B). (B) only happens inside of (A).
的（てき） - Speaking in the sphere of (A), (B). (B) can only be said within the sphere of (A).
He moved to an English speaking country. (A country within the English speaking world)
She is a national star. (Speaking in terms of the nation, she is a star)
As we can see here, when you want to convey something that can be said from a specific standpoint, 的（てき） will be a logical choice.