class Entry models Model tags models ManyToManyField Tag null True bla

class Entry(models.Model):
    ....
    tags = models.ManyToManyField(Tag, null=True, blank=True)

class Tag(models.Model):
    name = models.CharField(max_length=50, unique=True)
    slug = models.CharField(max_length=150, editable=False)
    ...