Writing systems:

The general attributes of writing systems can be placed into broad categories such as alphabets, syllabaries, or logographies. In the alphabetic category, there is a standard set of letters (basic written symbols or graphemes) of consonants and vowels that encode based on the general principle that the letters (or letter pair/groups) represent speech sounds.

In a syllabary, each symbol correlates to a syllable.

In a logography, each character represents a word, morpheme, or other semantic units. Alphabets typically use a set of 20-to-35 symbols to fully express a language, whereas syllabaries can have 80-to-100, and logographies can have several hundreds of symbols.

Writing systems were preceded by proto-writing, which used pictograms, ideograms and other mnemonic symbols. However, Proto-writing lacked the ability to capture and express a full range of thoughts and ideas.

Most Chinese characters are classified as logograms, let’s watch this interesing video:

The Roman calendar:

The Roman calendar changed its form several times between the founding of Rome and the fall of the Roman Empire. The common calendar widely used today is known as the Gregorian calendar and is a refinement of the Julian calendar, which lasted 365.25 days.

From at least the period of Augustus on, calendars were often inscribed in stone and displayed publicly. Such calendars are called fasti.

Here you have more information (in Spanish) about its origins, evolution and characteristics:

The Indo-European Languages:

The Indo-European languages are a family of several hundred related languages and dialects. The most widely spoken Indo-European languages by native speakers are Spanish, English, Hindi, Portuguese, Bengali, Russian, Persian and Punjabi, each with over 100 million speakers. Today, 46% of the human population speaks an Indo European language, by far the most of any language family, 

The Indo-European family includes most of the modern languages of Europe, and parts of Western, Central and South Asia. It was also predominant in ancient Anatolia (present-day Turkey), and the ancient Tarim Basin (present-day Northwest China) and most of Central Asia until the medieval Turkic migrations and Mongol invasions. With written evidence appearing since the Bronze Age in the form of the Anatolian languages and Mycenaean Greek, the Indo-European family is significant to the field of historical linguistics as possessing the second-longest recorded history, after the Afroasiatic family