How do they see you? | Basics Assassin's Creed (PC) Guide

No matter what you are doing, your every activity is closely watched both by guards and by other people. To check the attitude of the crowd you have is special indicator at your disposal, which changes colors according to the situation you are in. When the indicator is white, there is no problem at all. When the middle of the triangle is pulsing yellow, someone is watching you. When the middle is pulsing red, trouble is not far ahead. Wholly red triangle means you're in battle.

Indictator is white and you are safe.	Yellow in the middle means someone is watching you.
Pulsing red means that you are in trouble.	Red triangle means you need to choose weather to fight or run.

If you decide to run, breaking the line of sight changes the indicator to pulsing yellow. After that you just need to hide in the haystack or in the garden on the roof and wait till the chase is over.

On the groundyou can hide in the hay.

On the roof, in the gardens.

If you do not want to bring undue attention, you need to move around in way that does not disturb other people. In short, do not mess around, destroying pottery or pushing pedestrians. Using the B/Shift button you can gently push pedestrians out of your way. The best way, but the slowest one, is to act like a scholar. Simply push the A/Space Bar button and you're a saint, blending into the crowd.

Do not disturb other people, and you won't get their attention.

Blend.