Thes tudyo fp ulsating starst hrough photometric observations,s peciallyt imes eriesp hotometry, hasg rown from visual to single channel photometry, doublea nd triple channel and finallyC CD photometry. Thec ontinuousm easurement of the pulsatings tar, simultaneously with accurates ky measurements ands everal comparisons tars,h as allowed ah ugei ncrease in the detectabilityo fl ow amplitudep ulsations, andt he possiblec orrection of thinc loud anda tmospheric variability, whichc an occur at timescales of minutes,d ue to g-modes on the Eartha tmosphere. It hasa lsob een crucial to be able to usec omparisons brighter than the target star andl esst hanafewa rcminutes from the pulsatings tar, decreasing the noise introduced in the differential photometryd ue to noisei nt he comparisons. On 4m classt elescopes,a nd primef ocus on 2m classt elescopes,w ec an routinely achieve1mmag precision up to 19thm ag stars, allowingt he study of distants tars andp ossiblyd ifferent populations. To be able to measure multiple periodsp resent in non-radially pulsating stars, it is necessary to observet he star fors everal beat periods, andm ulti-sitec ampaigns,w ithn etworkss uch as the DeltaS cuti Networka nd the WholeE arth Telescope, forexample,h avealloweds uch long observations,l asting of the order of twot ofive months.O nt he data analysisside, corrections of the observationst imes to the barycenter of the solars ystem became necessary to join long data sets,a nd Monte Carlosimulations of the time seriesa llowed an efficient wayt oe stimate the detection limitsf or time seriesw ithg apsa nd multiperiodic, wheret he noised istribution is notP oissonic. Thed iscoveryo fm anyp ulsation modes in nonradially pulsating stars, as DeltaS cuti,r oAp, the Suna nd whited warf stars, hasa lloweds eismologicals tudiesm easuringa ccuratelys everal internalp ropertieso ft hesep ulsating stars, as each mode of pulsation is an independent measurement of the stellars tructure, andb othg-modes andp-modes in general sample alarge fraction of the star.I thas becomee vident thatmostt ypes of pulsators show amplitudev ariations on timescales of weekst oy ears, even when we canu ntangle the individualm odes,i .e., correct by the beatingo fn earbym odes.T hesec hanges arem ostl ikely on timescales comparablet ot he growth timescales of the different modes ands houldc arry detailedi nformationo nt he instabilitym echanism. Whited warf pulsators show the largest numbero fp ulsation modes detected after the Sun. Theirs tudyh as allowed as trongt esto n stellare volution andh ighd ensityp hysics,i ncluding theirs ecular time change rate, placing these starsi nl evelsc omparablet ol arge collider experiments.