texten
to text
Colloquial for writing and sending a short message (SMS) or a message via a messenger service such as WhatsApp.
Ich texte dir später, wann ich ankomme.
I'll text you later when I arrive.

to text / to write
Loading your saved state.
to text
Colloquial for writing and sending a short message (SMS) or a message via a messenger service such as WhatsApp.
Ich texte dir später, wann ich ankomme.
I'll text you later when I arrive.

The verb 'texten' is derived directly from the noun 'der Text' (the text). This formation is common in German, especially for modern activities.
Er hat den ganzen Vormittag an diesem wichtigen Text gearbeitet.
He worked on this important text all morning.
You can easily recognize the meaning of 'texten' from context. In everyday life, with reference to a mobile phone, it almost always means sending a message. In a professional context, it is about writing professional texts, and in a musical context, about song lyrics.
Kannst du mir kurz texten, wenn du fertig bist?
Can you text me quickly when you're done?
In the meaning 'to send a message', 'texten' is very colloquial and is used mainly in spoken language and informal chats.
Text mir mal ein Foto von deinem neuen Auto!
Text me a photo of your new car!
When you say whom you are writing a message to, that person is usually in the dative. The most common form is 'jemandem texten' (to text someone).
Ich muss meiner Mutter noch schnell texten, dass ich später komme.
I still need to quickly text my mother that I'll be coming later.
to write
'schreiben' and 'texten' can both mean that you formulate words in writing or send a message. 'schreiben' is the more general word and works for letters, emails, articles, assignments, or messages. 'texten' often sounds colloquial and especially refers to short messages by phone or messenger. It can also mean composing a text, but then it is less neutral than 'schreiben'. Learners may confuse the words because in everyday life you can hear both 'Ich schreibe dir' (I'll write/message you) and 'Ich texte dir' (I'll text you). The safer rule is: use 'schreiben' for almost all written texts, and 'texten' for quick phone messages.

Sie textet ihrem Bruder schnell, dass sie später nach Hause kommt.
She quickly texts her brother that she will come home later.
Nach dem Termin schreibe ich meiner Chefin eine kurze E-Mail.
After the appointment, I'll write my boss a short email.