This is called the regular past tense and applies to a large number of verbs.
For example:
* walk -> walked
* play -> played
* jump -> jumped
* talk -> talked
However, there are also a number of irregular verbs that don't follow this rule and have different past tense forms.
Examples:
* go -> went
* see -> saw
* eat -> ate
* have -> had
So while -ed is the most common ending for past tense verbs, it's important to remember that there are exceptions.