Morse code is made up of dots and dashes. How did telegraph operators keep from losing track of where one letter ended and another began?

Question

In the movies, morse code comes through so fast it’s hard to tell a dot from a dash. Hoe did they keep from getting lost?

In: 1001

Answer 1

My question is, what if the receiver misses the first few dots and dashes for some reason or they’re transmitted before he could start writing , how does he find out the first few letters or words?